dom/events/EventStateManager.cpp
author Masayuki Nakano <masayuki@d-toybox.com>
Mon, 18 Mar 2019 01:52:36 +0000
changeset 464720 d011dfe8368374923cb69a0ab510d6814cbf3ab1
parent 463954 d55401632cea92b6b2775ba278274b5490275876
child 465025 aa59ec8e0542373a561b259801dd84d2363b3daa
permissions -rw-r--r--
Bug 1533293 - part 3: Make editor and ContentEventHandler not use Selection::Extend() due to too slow r=m_kato `Selection::Extend()` is too slow but editor and ContentEventHandler use it in some places. We should make them use `Selection::SetStartAndEndInLimiter()` or `Selection::SetBaseAndExtentInLimiter()`. The former is usable only when caller guarantees the start point is prior to the end point in the DOM tree. Otherwise, we need to use the latter even though it's slower than the former. Differential Revision: https://phabricator.services.mozilla.com/D23462

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "mozilla/Attributes.h"
#include "mozilla/EventDispatcher.h"
#include "mozilla/EventStateManager.h"
#include "mozilla/EventStates.h"
#include "mozilla/HTMLEditor.h"
#include "mozilla/IMEStateManager.h"
#include "mozilla/MiscEvents.h"
#include "mozilla/MathAlgorithms.h"
#include "mozilla/MouseEvents.h"
#include "mozilla/TextComposition.h"
#include "mozilla/TextEditor.h"
#include "mozilla/TextEvents.h"
#include "mozilla/TouchEvents.h"
#include "mozilla/dom/ContentChild.h"
#include "mozilla/dom/DragEvent.h"
#include "mozilla/dom/Event.h"
#include "mozilla/dom/FrameLoaderBinding.h"
#include "mozilla/dom/MouseEventBinding.h"
#include "mozilla/dom/TabChild.h"
#include "mozilla/dom/TabParent.h"
#include "mozilla/dom/UIEvent.h"
#include "mozilla/dom/UIEventBinding.h"
#include "mozilla/dom/WheelEventBinding.h"

#include "ContentEventHandler.h"
#include "IMEContentObserver.h"
#include "WheelHandlingHelper.h"

#include "nsCommandParams.h"
#include "nsCOMPtr.h"
#include "nsCopySupport.h"
#include "nsFocusManager.h"
#include "nsGenericHTMLElement.h"
#include "nsIClipboard.h"
#include "nsIContent.h"
#include "nsIContentInlines.h"
#include "mozilla/dom/Document.h"
#include "nsIFrame.h"
#include "nsFrameLoaderOwner.h"
#include "nsITextControlElement.h"
#include "nsIWidget.h"
#include "nsPresContext.h"
#include "nsIPresShell.h"
#include "nsGkAtoms.h"
#include "nsIFormControl.h"
#include "nsComboboxControlFrame.h"
#include "nsIScrollableFrame.h"
#include "nsIDOMXULControlElement.h"
#include "nsNameSpaceManager.h"
#include "nsIBaseWindow.h"
#include "nsFrameSelection.h"
#include "nsPIDOMWindow.h"
#include "nsPIWindowRoot.h"
#include "nsIWebNavigation.h"
#include "nsIContentViewer.h"
#include "nsFrameManager.h"
#include "nsITabChild.h"
#include "nsPluginFrame.h"
#include "nsMenuPopupFrame.h"

#include "nsIObserverService.h"
#include "nsIDocShell.h"
#include "nsIMozBrowserFrame.h"

#include "nsSubDocumentFrame.h"
#include "nsLayoutUtils.h"
#include "nsIInterfaceRequestorUtils.h"
#include "nsUnicharUtils.h"
#include "nsContentUtils.h"

#include "imgIContainer.h"
#include "nsIProperties.h"
#include "nsISupportsPrimitives.h"

#include "nsServiceManagerUtils.h"
#include "nsITimer.h"
#include "nsFontMetrics.h"
#include "nsIDragService.h"
#include "nsIDragSession.h"
#include "mozilla/dom/DataTransfer.h"
#include "nsContentAreaDragDrop.h"
#ifdef MOZ_XUL
#  include "nsTreeBodyFrame.h"
#endif
#include "nsIController.h"
#include "nsICommandParams.h"
#include "mozilla/Services.h"
#include "mozilla/dom/ContentParent.h"
#include "mozilla/dom/HTMLLabelElement.h"
#include "mozilla/dom/Selection.h"

#include "mozilla/Preferences.h"
#include "mozilla/LookAndFeel.h"
#include "GeckoProfiler.h"
#include "Units.h"
#include "nsIObjectLoadingContent.h"

#ifdef XP_MACOSX
#  import <ApplicationServices/ApplicationServices.h>
#endif

namespace mozilla {

using namespace dom;

static const LayoutDeviceIntPoint kInvalidRefPoint =
    LayoutDeviceIntPoint(-1, -1);

static uint32_t gMouseOrKeyboardEventCounter = 0;
static nsITimer* gUserInteractionTimer = nullptr;
static nsITimerCallback* gUserInteractionTimerCallback = nullptr;

static const double kCursorLoadingTimeout = 1000;  // ms
static AutoWeakFrame gLastCursorSourceFrame;
static TimeStamp gLastCursorUpdateTime;

static inline int32_t RoundDown(double aDouble) {
  return (aDouble > 0) ? static_cast<int32_t>(floor(aDouble))
                       : static_cast<int32_t>(ceil(aDouble));
}

/******************************************************************/
/* mozilla::UITimerCallback                                       */
/******************************************************************/

class UITimerCallback final : public nsITimerCallback, public nsINamed {
 public:
  UITimerCallback() : mPreviousCount(0) {}
  NS_DECL_ISUPPORTS
  NS_DECL_NSITIMERCALLBACK
  NS_DECL_NSINAMED
 private:
  ~UITimerCallback() = default;
  uint32_t mPreviousCount;
};

NS_IMPL_ISUPPORTS(UITimerCallback, nsITimerCallback, nsINamed)

// If aTimer is nullptr, this method always sends "user-interaction-inactive"
// notification.
NS_IMETHODIMP
UITimerCallback::Notify(nsITimer* aTimer) {
  nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
  if (!obs) return NS_ERROR_FAILURE;
  if ((gMouseOrKeyboardEventCounter == mPreviousCount) || !aTimer) {
    gMouseOrKeyboardEventCounter = 0;
    obs->NotifyObservers(nullptr, "user-interaction-inactive", nullptr);
    if (gUserInteractionTimer) {
      gUserInteractionTimer->Cancel();
      NS_RELEASE(gUserInteractionTimer);
    }
  } else {
    obs->NotifyObservers(nullptr, "user-interaction-active", nullptr);
    EventStateManager::UpdateUserActivityTimer();
  }
  mPreviousCount = gMouseOrKeyboardEventCounter;
  return NS_OK;
}

NS_IMETHODIMP
UITimerCallback::GetName(nsACString& aName) {
  aName.AssignLiteral("UITimerCallback_timer");
  return NS_OK;
}

/******************************************************************/
/* mozilla::OverOutElementsWrapper                                */
/******************************************************************/

OverOutElementsWrapper::OverOutElementsWrapper() : mLastOverFrame(nullptr) {}

OverOutElementsWrapper::~OverOutElementsWrapper() = default;

NS_IMPL_CYCLE_COLLECTION(OverOutElementsWrapper, mLastOverElement,
                         mFirstOverEventElement, mFirstOutEventElement)
NS_IMPL_CYCLE_COLLECTING_ADDREF(OverOutElementsWrapper)
NS_IMPL_CYCLE_COLLECTING_RELEASE(OverOutElementsWrapper)

NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(OverOutElementsWrapper)
  NS_INTERFACE_MAP_ENTRY(nsISupports)
NS_INTERFACE_MAP_END

/******************************************************************/
/* mozilla::EventStateManager                                     */
/******************************************************************/

static uint32_t sESMInstanceCount = 0;

uint64_t EventStateManager::sUserInputCounter = 0;
int32_t EventStateManager::sUserInputEventDepth = 0;
int32_t EventStateManager::sUserKeyboardEventDepth = 0;
bool EventStateManager::sNormalLMouseEventInProcess = false;
EventStateManager* EventStateManager::sActiveESM = nullptr;
Document* EventStateManager::sMouseOverDocument = nullptr;
AutoWeakFrame EventStateManager::sLastDragOverFrame = nullptr;
LayoutDeviceIntPoint EventStateManager::sPreLockPoint =
    LayoutDeviceIntPoint(0, 0);
LayoutDeviceIntPoint EventStateManager::sLastRefPoint = kInvalidRefPoint;
CSSIntPoint EventStateManager::sLastScreenPoint = CSSIntPoint(0, 0);
LayoutDeviceIntPoint EventStateManager::sSynthCenteringPoint = kInvalidRefPoint;
CSSIntPoint EventStateManager::sLastClientPoint = CSSIntPoint(0, 0);
bool EventStateManager::sIsPointerLocked = false;
// Reference to the pointer locked element.
nsWeakPtr EventStateManager::sPointerLockedElement;
// Reference to the document which requested pointer lock.
nsWeakPtr EventStateManager::sPointerLockedDoc;
nsCOMPtr<nsIContent> EventStateManager::sDragOverContent = nullptr;
TimeStamp EventStateManager::sLatestUserInputStart;
TimeStamp EventStateManager::sHandlingInputStart;

EventStateManager::WheelPrefs* EventStateManager::WheelPrefs::sInstance =
    nullptr;
bool EventStateManager::WheelPrefs::sWheelEventsEnabledOnPlugins = true;
bool EventStateManager::WheelPrefs::sIsAutoDirEnabled = false;
bool EventStateManager::WheelPrefs::sHonoursRootForAutoDir = false;
EventStateManager::DeltaAccumulator*
    EventStateManager::DeltaAccumulator::sInstance = nullptr;

constexpr const StyleCursorKind kInvalidCursorKind =
    static_cast<StyleCursorKind>(255);

EventStateManager::EventStateManager()
    : mLockCursor(kInvalidCursorKind),
      mLastFrameConsumedSetCursor(false),
      mCurrentTarget(nullptr),
      // init d&d gesture state machine variables
      mGestureDownPoint(0, 0),
      mGestureModifiers(0),
      mGestureDownButtons(0),
      mPresContext(nullptr),
      mLClickCount(0),
      mMClickCount(0),
      mRClickCount(0),
      mInTouchDrag(false),
      m_haveShutdown(false) {
  if (sESMInstanceCount == 0) {
    gUserInteractionTimerCallback = new UITimerCallback();
    if (gUserInteractionTimerCallback) NS_ADDREF(gUserInteractionTimerCallback);
    UpdateUserActivityTimer();
  }
  ++sESMInstanceCount;
  WheelTransaction::InitializeStatics();
}

nsresult EventStateManager::UpdateUserActivityTimer() {
  if (!gUserInteractionTimerCallback) return NS_OK;

  if (!gUserInteractionTimer) {
    gUserInteractionTimer =
        NS_NewTimer(SystemGroup::EventTargetFor(TaskCategory::Other)).take();
  }

  if (gUserInteractionTimer) {
    gUserInteractionTimer->InitWithCallback(gUserInteractionTimerCallback,
                                            NS_USER_INTERACTION_INTERVAL,
                                            nsITimer::TYPE_ONE_SHOT);
  }
  return NS_OK;
}

nsresult EventStateManager::Init() {
  nsCOMPtr<nsIObserverService> observerService =
      mozilla::services::GetObserverService();
  if (!observerService) return NS_ERROR_FAILURE;

  observerService->AddObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID, true);

  if (sESMInstanceCount == 1) {
    Prefs::Init();
  }

  return NS_OK;
}

EventStateManager::~EventStateManager() {
  ReleaseCurrentIMEContentObserver();

  if (sActiveESM == this) {
    sActiveESM = nullptr;
  }
  if (Prefs::ClickHoldContextMenu()) KillClickHoldTimer();

  if (mDocument == sMouseOverDocument) sMouseOverDocument = nullptr;

  --sESMInstanceCount;
  if (sESMInstanceCount == 0) {
    WheelTransaction::Shutdown();
    if (gUserInteractionTimerCallback) {
      gUserInteractionTimerCallback->Notify(nullptr);
      NS_RELEASE(gUserInteractionTimerCallback);
    }
    if (gUserInteractionTimer) {
      gUserInteractionTimer->Cancel();
      NS_RELEASE(gUserInteractionTimer);
    }
    WheelPrefs::Shutdown();
    DeltaAccumulator::Shutdown();
  }

  if (sDragOverContent && sDragOverContent->OwnerDoc() == mDocument) {
    sDragOverContent = nullptr;
  }

  if (!m_haveShutdown) {
    Shutdown();

    // Don't remove from Observer service in Shutdown because Shutdown also
    // gets called from xpcom shutdown observer.  And we don't want to remove
    // from the service in that case.

    nsCOMPtr<nsIObserverService> observerService =
        mozilla::services::GetObserverService();
    if (observerService) {
      observerService->RemoveObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID);
    }
  }
}

nsresult EventStateManager::Shutdown() {
  m_haveShutdown = true;
  return NS_OK;
}

NS_IMETHODIMP
EventStateManager::Observe(nsISupports* aSubject, const char* aTopic,
                           const char16_t* someData) {
  if (!nsCRT::strcmp(aTopic, NS_XPCOM_SHUTDOWN_OBSERVER_ID)) {
    Shutdown();
  }

  return NS_OK;
}

NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(EventStateManager)
  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIObserver)
  NS_INTERFACE_MAP_ENTRY(nsIObserver)
  NS_INTERFACE_MAP_ENTRY(nsISupportsWeakReference)
NS_INTERFACE_MAP_END

NS_IMPL_CYCLE_COLLECTING_ADDREF(EventStateManager)
NS_IMPL_CYCLE_COLLECTING_RELEASE(EventStateManager)

NS_IMPL_CYCLE_COLLECTION(EventStateManager, mCurrentTargetContent,
                         mGestureDownContent, mGestureDownFrameOwner,
                         mLastLeftMouseDownContent, mLastMiddleMouseDownContent,
                         mLastRightMouseDownContent, mActiveContent,
                         mHoverContent, mURLTargetContent,
                         mMouseEnterLeaveHelper, mPointersEnterLeaveHelper,
                         mDocument, mIMEContentObserver, mAccessKeys)

void EventStateManager::ReleaseCurrentIMEContentObserver() {
  if (mIMEContentObserver) {
    mIMEContentObserver->DisconnectFromEventStateManager();
  }
  mIMEContentObserver = nullptr;
}

void EventStateManager::OnStartToObserveContent(
    IMEContentObserver* aIMEContentObserver) {
  if (mIMEContentObserver == aIMEContentObserver) {
    return;
  }
  ReleaseCurrentIMEContentObserver();
  mIMEContentObserver = aIMEContentObserver;
}

void EventStateManager::OnStopObservingContent(
    IMEContentObserver* aIMEContentObserver) {
  aIMEContentObserver->DisconnectFromEventStateManager();
  NS_ENSURE_TRUE_VOID(mIMEContentObserver == aIMEContentObserver);
  mIMEContentObserver = nullptr;
}

void EventStateManager::TryToFlushPendingNotificationsToIME() {
  if (mIMEContentObserver) {
    mIMEContentObserver->TryToFlushPendingNotifications(true);
  }
}

static bool IsMessageMouseUserActivity(EventMessage aMessage) {
  return aMessage == eMouseMove || aMessage == eMouseUp ||
         aMessage == eMouseDown || aMessage == eMouseAuxClick ||
         aMessage == eMouseDoubleClick || aMessage == eMouseClick ||
         aMessage == eMouseActivate || aMessage == eMouseLongTap;
}

static bool IsMessageGamepadUserActivity(EventMessage aMessage) {
  return aMessage == eGamepadButtonDown || aMessage == eGamepadButtonUp ||
         aMessage == eGamepadAxisMove;
}

nsresult EventStateManager::PreHandleEvent(nsPresContext* aPresContext,
                                           WidgetEvent* aEvent,
                                           nsIFrame* aTargetFrame,
                                           nsIContent* aTargetContent,
                                           nsEventStatus* aStatus,
                                           nsIContent* aOverrideClickTarget) {
  NS_ENSURE_ARG_POINTER(aStatus);
  NS_ENSURE_ARG(aPresContext);
  if (!aEvent) {
    NS_ERROR("aEvent is null.  This should never happen.");
    return NS_ERROR_NULL_POINTER;
  }

  NS_WARNING_ASSERTION(
      !aTargetFrame || !aTargetFrame->GetContent() ||
          aTargetFrame->GetContent() == aTargetContent ||
          aTargetFrame->GetContent()->GetFlattenedTreeParent() ==
              aTargetContent ||
          aTargetFrame->IsGeneratedContentFrame(),
      "aTargetFrame should be related with aTargetContent");
#if DEBUG
  if (aTargetFrame && aTargetFrame->IsGeneratedContentFrame()) {
    nsCOMPtr<nsIContent> targetContent;
    aTargetFrame->GetContentForEvent(aEvent, getter_AddRefs(targetContent));
    MOZ_ASSERT(aTargetContent == targetContent,
               "Unexpected target for generated content frame!");
  }
#endif

  mCurrentTarget = aTargetFrame;
  mCurrentTargetContent = nullptr;

  // Do not take account eMouseEnterIntoWidget/ExitFromWidget so that loading
  // a page when user is not active doesn't change the state to active.
  WidgetMouseEvent* mouseEvent = aEvent->AsMouseEvent();
  if (aEvent->IsTrusted() &&
      ((mouseEvent && mouseEvent->IsReal() &&
        IsMessageMouseUserActivity(mouseEvent->mMessage)) ||
       aEvent->mClass == eWheelEventClass ||
       aEvent->mClass == ePointerEventClass ||
       aEvent->mClass == eTouchEventClass ||
       aEvent->mClass == eKeyboardEventClass ||
       IsMessageGamepadUserActivity(aEvent->mMessage))) {
    if (gMouseOrKeyboardEventCounter == 0) {
      nsCOMPtr<nsIObserverService> obs =
          mozilla::services::GetObserverService();
      if (obs) {
        obs->NotifyObservers(nullptr, "user-interaction-active", nullptr);
        UpdateUserActivityTimer();
      }
    }
    ++gMouseOrKeyboardEventCounter;

    nsCOMPtr<nsINode> node = aTargetContent;
    if (node && (aEvent->mMessage == eKeyUp || aEvent->mMessage == eMouseUp ||
                 aEvent->mMessage == eWheel || aEvent->mMessage == eTouchEnd ||
                 aEvent->mMessage == ePointerUp)) {
      Document* doc = node->OwnerDoc();
      while (doc) {
        doc->SetUserHasInteracted();
        doc = nsContentUtils::IsChildOfSameType(doc) ? doc->GetParentDocument()
                                                     : nullptr;
      }
    }
  }

  WheelTransaction::OnEvent(aEvent);

  // Focus events don't necessarily need a frame.
  if (!mCurrentTarget && !aTargetContent) {
    NS_ERROR("mCurrentTarget and aTargetContent are null");
    return NS_ERROR_NULL_POINTER;
  }
#ifdef DEBUG
  if (aEvent->HasDragEventMessage() && sIsPointerLocked) {
    NS_ASSERTION(
        sIsPointerLocked,
        "sIsPointerLocked is true. Drag events should be suppressed when "
        "the pointer is locked.");
  }
#endif
  // Store last known screenPoint and clientPoint so pointer lock
  // can use these values as constants.
  if (aEvent->IsTrusted() &&
      ((mouseEvent && mouseEvent->IsReal()) ||
       aEvent->mClass == eWheelEventClass) &&
      !sIsPointerLocked) {
    sLastScreenPoint =
        Event::GetScreenCoords(aPresContext, aEvent, aEvent->mRefPoint);
    sLastClientPoint = Event::GetClientCoords(
        aPresContext, aEvent, aEvent->mRefPoint, CSSIntPoint(0, 0));
  }

  *aStatus = nsEventStatus_eIgnore;

  if (aEvent->mClass == eQueryContentEventClass) {
    HandleQueryContentEvent(aEvent->AsQueryContentEvent());
    return NS_OK;
  }

  WidgetTouchEvent* touchEvent = aEvent->AsTouchEvent();
  if (touchEvent && mInTouchDrag) {
    if (touchEvent->mMessage == eTouchMove) {
      GenerateDragGesture(aPresContext, touchEvent);
    } else {
      mInTouchDrag = false;
      StopTrackingDragGesture();
    }
  }

  PointerEventHandler::UpdateActivePointerState(mouseEvent);

  switch (aEvent->mMessage) {
    case eContextMenu:
      if (sIsPointerLocked) {
        return NS_ERROR_DOM_INVALID_STATE_ERR;
      }
      break;
    case eMouseTouchDrag:
      mInTouchDrag = true;
      BeginTrackingDragGesture(aPresContext, mouseEvent, aTargetFrame);
      break;
    case eMouseDown: {
      switch (mouseEvent->button) {
        case WidgetMouseEvent::eLeftButton:
          BeginTrackingDragGesture(aPresContext, mouseEvent, aTargetFrame);
          mLClickCount = mouseEvent->mClickCount;
          SetClickCount(mouseEvent, aStatus);
          sNormalLMouseEventInProcess = true;
          break;
        case WidgetMouseEvent::eMiddleButton:
          mMClickCount = mouseEvent->mClickCount;
          SetClickCount(mouseEvent, aStatus);
          break;
        case WidgetMouseEvent::eRightButton:
          mRClickCount = mouseEvent->mClickCount;
          SetClickCount(mouseEvent, aStatus);
          break;
      }
      NotifyTargetUserActivation(aEvent, aTargetContent);
      break;
    }
    case eMouseUp: {
      switch (mouseEvent->button) {
        case WidgetMouseEvent::eLeftButton:
          if (Prefs::ClickHoldContextMenu()) {
            KillClickHoldTimer();
          }
          mInTouchDrag = false;
          StopTrackingDragGesture();
          sNormalLMouseEventInProcess = false;
          // then fall through...
          MOZ_FALLTHROUGH;
        case WidgetMouseEvent::eRightButton:
        case WidgetMouseEvent::eMiddleButton:
          RefPtr<EventStateManager> esm =
              ESMFromContentOrThis(aOverrideClickTarget);
          esm->SetClickCount(mouseEvent, aStatus, aOverrideClickTarget);
          break;
      }
      break;
    }
    case eMouseEnterIntoWidget:
      // In some cases on e10s eMouseEnterIntoWidget
      // event was sent twice into child process of content.
      // (From specific widget code (sending is not permanent) and
      // from ESM::DispatchMouseOrPointerEvent (sending is permanent)).
      // IsCrossProcessForwardingStopped() helps to suppress sending accidental
      // event from widget code.
      aEvent->StopCrossProcessForwarding();
      break;
    case eMouseExitFromWidget:
      // If this is a remote frame, we receive eMouseExitFromWidget from the
      // parent the mouse exits our content. Since the parent may update the
      // cursor while the mouse is outside our frame, and since PuppetWidget
      // caches the current cursor internally, re-entering our content (say from
      // over a window edge) wont update the cursor if the cached value and the
      // current cursor match. So when the mouse exits a remote frame, clear the
      // cached widget cursor so a proper update will occur when the mouse
      // re-enters.
      if (XRE_IsContentProcess()) {
        ClearCachedWidgetCursor(mCurrentTarget);
      }

      // IsCrossProcessForwardingStopped() helps to suppress double event
      // sending into process of content. For more information see comment
      // above, at eMouseEnterIntoWidget case.
      aEvent->StopCrossProcessForwarding();

      // If the event is not a top-level window exit, then it's not
      // really an exit --- we may have traversed widget boundaries but
      // we're still in our toplevel window.
      if (mouseEvent->mExitFrom != WidgetMouseEvent::eTopLevel) {
        // Treat it as a synthetic move so we don't generate spurious
        // "exit" or "move" events.  Any necessary "out" or "over" events
        // will be generated by GenerateMouseEnterExit
        mouseEvent->mMessage = eMouseMove;
        mouseEvent->mReason = WidgetMouseEvent::eSynthesized;
        // then fall through...
      } else {
        // We should synthetize corresponding pointer events
        GeneratePointerEnterExit(ePointerLeave, mouseEvent);
        GenerateMouseEnterExit(mouseEvent);
        // This is a window level mouse exit event and should stop here
        aEvent->mMessage = eVoidEvent;
        break;
      }
      MOZ_FALLTHROUGH;
    case eMouseMove:
    case ePointerDown:
      if (aEvent->mMessage == ePointerDown) {
        PointerEventHandler::ImplicitlyCapturePointer(aTargetFrame, aEvent);
        if (mouseEvent->inputSource != MouseEvent_Binding::MOZ_SOURCE_TOUCH) {
          NotifyTargetUserActivation(aEvent, aTargetContent);
        }
      }
      MOZ_FALLTHROUGH;
    case ePointerMove: {
      // on the Mac, GenerateDragGesture() may not return until the drag
      // has completed and so |aTargetFrame| may have been deleted (moving
      // a bookmark, for example).  If this is the case, however, we know
      // that ClearFrameRefs() has been called and it cleared out
      // |mCurrentTarget|. As a result, we should pass |mCurrentTarget|
      // into UpdateCursor().
      if (!mInTouchDrag) {
        GenerateDragGesture(aPresContext, mouseEvent);
      }
      UpdateCursor(aPresContext, aEvent, mCurrentTarget, aStatus);

      UpdateLastRefPointOfMouseEvent(mouseEvent);
      if (sIsPointerLocked) {
        ResetPointerToWindowCenterWhilePointerLocked(mouseEvent);
      }
      UpdateLastPointerPosition(mouseEvent);

      GenerateMouseEnterExit(mouseEvent);
      // Flush pending layout changes, so that later mouse move events
      // will go to the right nodes.
      FlushPendingEvents(aPresContext);
      break;
    }
    case ePointerGotCapture:
      GenerateMouseEnterExit(mouseEvent);
      break;
    case eDragStart:
      if (Prefs::ClickHoldContextMenu()) {
        // an external drag gesture event came in, not generated internally
        // by Gecko. Make sure we get rid of the click-hold timer.
        KillClickHoldTimer();
      }
      break;
    case eDragOver:
      // Send the enter/exit events before eDrop.
      GenerateDragDropEnterExit(aPresContext, aEvent->AsDragEvent());
      break;

    case eKeyPress: {
      WidgetKeyboardEvent* keyEvent = aEvent->AsKeyboardEvent();
      if (keyEvent->ModifiersMatchWithAccessKey(AccessKeyType::eChrome) ||
          keyEvent->ModifiersMatchWithAccessKey(AccessKeyType::eContent)) {
        // If the eKeyPress event will be sent to a remote process, this
        // process needs to wait reply from the remote process for checking if
        // preceding eKeyDown event is consumed.  If preceding eKeyDown event
        // is consumed in the remote process, TabChild won't send the event
        // back to this process.  So, only when this process receives a reply
        // eKeyPress event in TabParent, we should handle accesskey in this
        // process.
        if (IsRemoteTarget(GetFocusedContent())) {
          // However, if there is no accesskey target for the key combination,
          // we don't need to wait reply from the remote process.  Otherwise,
          // Mark the event as waiting reply from remote process and stop
          // propagation in this process.
          if (CheckIfEventMatchesAccessKey(keyEvent, aPresContext)) {
            keyEvent->StopPropagation();
            keyEvent->MarkAsWaitingReplyFromRemoteProcess();
          }
        }
        // If the event target is in this process, we can handle accesskey now
        // since if preceding eKeyDown event was consumed, eKeyPress event
        // won't be dispatched by widget.  So, coming eKeyPress event means
        // that the preceding eKeyDown event wasn't consumed in this case.
        else {
          AutoTArray<uint32_t, 10> accessCharCodes;
          keyEvent->GetAccessKeyCandidates(accessCharCodes);

          if (HandleAccessKey(keyEvent, aPresContext, accessCharCodes)) {
            *aStatus = nsEventStatus_eConsumeNoDefault;
          }
        }
      }
    }
      // then fall through...
      MOZ_FALLTHROUGH;
    case eKeyDown:
      if (aEvent->mMessage == eKeyDown) {
        NotifyTargetUserActivation(aEvent, aTargetContent);
      }
      MOZ_FALLTHROUGH;
    case eKeyUp: {
      nsIContent* content = GetFocusedContent();
      if (content) mCurrentTargetContent = content;

      // NOTE: Don't refer TextComposition::IsComposing() since UI Events
      //       defines that KeyboardEvent.isComposing is true when it's
      //       dispatched after compositionstart and compositionend.
      //       TextComposition::IsComposing() is false even before
      //       compositionend if there is no composing string.
      //       And also don't expose other document's composition state.
      //       A native IME context is typically shared by multiple documents.
      //       So, don't use GetTextCompositionFor(nsIWidget*) here.
      RefPtr<TextComposition> composition =
          IMEStateManager::GetTextCompositionFor(aPresContext);
      aEvent->AsKeyboardEvent()->mIsComposing = !!composition;

      // Widget may need to perform default action for specific keyboard
      // event if it's not consumed.  In this case, widget has already marked
      // the event as "waiting reply from remote process".  However, we need
      // to reset it if the target (focused content) isn't in a remote process
      // because PresShell needs to check if it's marked as so before
      // dispatching events into the DOM tree.
      if (aEvent->IsWaitingReplyFromRemoteProcess() &&
          !aEvent->PropagationStopped() && !IsRemoteTarget(content)) {
        aEvent->ResetWaitingReplyFromRemoteProcessState();
      }
    } break;
    case eWheel:
    case eWheelOperationStart:
    case eWheelOperationEnd: {
      NS_ASSERTION(aEvent->IsTrusted(),
                   "Untrusted wheel event shouldn't be here");

      nsIContent* content = GetFocusedContent();
      if (content) {
        mCurrentTargetContent = content;
      }

      if (aEvent->mMessage != eWheel) {
        break;
      }

      WidgetWheelEvent* wheelEvent = aEvent->AsWheelEvent();
      WheelPrefs::GetInstance()->ApplyUserPrefsToDelta(wheelEvent);

      // If we won't dispatch a DOM event for this event, nothing to do anymore.
      if (!wheelEvent->IsAllowedToDispatchDOMEvent()) {
        break;
      }

      // Init lineOrPageDelta values for line scroll events for some devices
      // on some platforms which might dispatch wheel events which don't have
      // lineOrPageDelta values.  And also, if delta values are customized by
      // prefs, this recomputes them.
      DeltaAccumulator::GetInstance()->InitLineOrPageDelta(aTargetFrame, this,
                                                           wheelEvent);
    } break;
    case eSetSelection: {
      nsCOMPtr<nsIContent> focusedContent = GetFocusedContent();
      IMEStateManager::HandleSelectionEvent(aPresContext, focusedContent,
                                            aEvent->AsSelectionEvent());
      break;
    }
    case eContentCommandCut:
    case eContentCommandCopy:
    case eContentCommandPaste:
    case eContentCommandDelete:
    case eContentCommandUndo:
    case eContentCommandRedo:
    case eContentCommandPasteTransferable:
    case eContentCommandLookUpDictionary:
      DoContentCommandEvent(aEvent->AsContentCommandEvent());
      break;
    case eContentCommandScroll:
      DoContentCommandScrollEvent(aEvent->AsContentCommandEvent());
      break;
    case eCompositionStart:
      if (aEvent->IsTrusted()) {
        // If the event is trusted event, set the selected text to data of
        // composition event.
        WidgetCompositionEvent* compositionEvent = aEvent->AsCompositionEvent();
        WidgetQueryContentEvent selectedText(true, eQuerySelectedText,
                                             compositionEvent->mWidget);
        HandleQueryContentEvent(&selectedText);
        NS_ASSERTION(selectedText.mSucceeded, "Failed to get selected text");
        compositionEvent->mData = selectedText.mReply.mString;
      }
      break;
    case eTouchStart:
      SetGestureDownPoint(aEvent->AsTouchEvent());
      break;
    case eTouchEnd:
      NotifyTargetUserActivation(aEvent, aTargetContent);
      break;
    default:
      break;
  }
  return NS_OK;
}

static bool IsTextInput(nsIContent* aContent) {
  MOZ_ASSERT(aContent);
  if (!aContent->IsElement()) {
    return false;
  }
  TextEditor* textEditor = aContent->AsElement()->GetTextEditorInternal();
  return textEditor && !textEditor->IsReadonly();
}

void EventStateManager::NotifyTargetUserActivation(WidgetEvent* aEvent,
                                                   nsIContent* aTargetContent) {
  if (!aEvent->IsTrusted()) {
    return;
  }

  WidgetMouseEvent* mouseEvent = aEvent->AsMouseEvent();
  if (mouseEvent && !mouseEvent->IsReal()) {
    return;
  }

  nsCOMPtr<nsINode> node = aTargetContent;
  if (!node) {
    return;
  }

  Document* doc = node->OwnerDoc();
  if (!doc || doc->HasBeenUserGestureActivated()) {
    return;
  }

  // Don't activate if the target content of the event is contentEditable or
  // is inside an editable document, or is a text input control. Activating
  // due to typing/clicking on a text input would be surprising user experience.
  if (aTargetContent->IsEditable() || IsTextInput(aTargetContent)) {
    return;
  }

  // Don't gesture activate for key events for keys which are likely
  // to be interaction with the browser, OS.
  WidgetKeyboardEvent* keyEvent = aEvent->AsKeyboardEvent();
  if (keyEvent && !keyEvent->CanUserGestureActivateTarget()) {
    return;
  }

  // Touch gestures that end outside the drag target were touches that turned
  // into scroll/pan/swipe actions. We don't want to gesture activate on such
  // actions, we want to only gesture activate on touches that are taps.
  // That is, touches that end in roughly the same place that they started.
  if (aEvent->mMessage == eTouchEnd && aEvent->AsTouchEvent() &&
      IsEventOutsideDragThreshold(aEvent->AsTouchEvent())) {
    return;
  }

  MOZ_ASSERT(aEvent->mMessage == eKeyDown || aEvent->mMessage == eMouseDown ||
             aEvent->mMessage == ePointerDown || aEvent->mMessage == eTouchEnd);
  doc->NotifyUserGestureActivation();
}

already_AddRefed<EventStateManager> EventStateManager::ESMFromContentOrThis(
    nsIContent* aContent) {
  if (aContent) {
    nsIPresShell* shell = aContent->OwnerDoc()->GetShell();
    if (shell) {
      nsPresContext* prescontext = shell->GetPresContext();
      if (prescontext) {
        RefPtr<EventStateManager> esm = prescontext->EventStateManager();
        if (esm) {
          return esm.forget();
        }
      }
    }
  }

  RefPtr<EventStateManager> esm = this;
  return esm.forget();
}

void EventStateManager::HandleQueryContentEvent(
    WidgetQueryContentEvent* aEvent) {
  switch (aEvent->mMessage) {
    case eQuerySelectedText:
    case eQueryTextContent:
    case eQueryCaretRect:
    case eQueryTextRect:
    case eQueryEditorRect:
      if (!IsTargetCrossProcess(aEvent)) {
        break;
      }
      // Will not be handled locally, remote the event
      GetCrossProcessTarget()->HandleQueryContentEvent(*aEvent);
      return;
    // Following events have not been supported in e10s mode yet.
    case eQueryContentState:
    case eQuerySelectionAsTransferable:
    case eQueryCharacterAtPoint:
    case eQueryDOMWidgetHittest:
    case eQueryTextRectArray:
      break;
    default:
      return;
  }

  // If there is an IMEContentObserver, we need to handle QueryContentEvent
  // with it.
  if (mIMEContentObserver) {
    RefPtr<IMEContentObserver> contentObserver = mIMEContentObserver;
    contentObserver->HandleQueryContentEvent(aEvent);
    return;
  }

  ContentEventHandler handler(mPresContext);
  handler.HandleQueryContentEvent(aEvent);
}

static AccessKeyType GetAccessKeyTypeFor(nsISupports* aDocShell) {
  nsCOMPtr<nsIDocShellTreeItem> treeItem(do_QueryInterface(aDocShell));
  if (!treeItem) {
    return AccessKeyType::eNone;
  }

  switch (treeItem->ItemType()) {
    case nsIDocShellTreeItem::typeChrome:
      return AccessKeyType::eChrome;
    case nsIDocShellTreeItem::typeContent:
      return AccessKeyType::eContent;
    default:
      return AccessKeyType::eNone;
  }
}

static bool IsAccessKeyTarget(nsIContent* aContent, nsIFrame* aFrame,
                              nsAString& aKey) {
  // Use GetAttr because we want Unicode case=insensitive matching
  // XXXbz shouldn't this be case-sensitive, per spec?
  nsString contentKey;
  if (!aContent->IsElement() ||
      !aContent->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::accesskey,
                                      contentKey) ||
      !contentKey.Equals(aKey, nsCaseInsensitiveStringComparator()))
    return false;

  if (!aContent->OwnerDoc()->IsXULDocument() && !aContent->IsXULElement())
    return true;

  // For XUL we do visibility checks.
  if (!aFrame) return false;

  if (aFrame->IsFocusable()) return true;

  if (!aFrame->IsVisibleConsideringAncestors()) return false;

  // XUL controls can be activated.
  nsCOMPtr<nsIDOMXULControlElement> control =
      aContent->AsElement()->AsXULControl();
  if (control) return true;

  // HTML area, label and legend elements are never focusable, so
  // we need to check for them explicitly before giving up.
  if (aContent->IsAnyOfHTMLElements(nsGkAtoms::area, nsGkAtoms::label,
                                    nsGkAtoms::legend)) {
    return true;
  }

  // XUL label elements are never focusable, so we need to check for them
  // explicitly before giving up.
  if (aContent->IsXULElement(nsGkAtoms::label)) {
    return true;
  }

  return false;
}

bool EventStateManager::CheckIfEventMatchesAccessKey(
    WidgetKeyboardEvent* aEvent, nsPresContext* aPresContext) {
  AutoTArray<uint32_t, 10> accessCharCodes;
  aEvent->GetAccessKeyCandidates(accessCharCodes);
  return WalkESMTreeToHandleAccessKey(const_cast<WidgetKeyboardEvent*>(aEvent),
                                      aPresContext, accessCharCodes, nullptr,
                                      eAccessKeyProcessingNormal, false);
}

bool EventStateManager::LookForAccessKeyAndExecute(
    nsTArray<uint32_t>& aAccessCharCodes, bool aIsTrustedEvent, bool aIsRepeat,
    bool aExecute) {
  int32_t count, start = -1;
  nsIContent* focusedContent = GetFocusedContent();
  if (focusedContent) {
    start = mAccessKeys.IndexOf(focusedContent);
    if (start == -1 && focusedContent->GetBindingParent())
      start = mAccessKeys.IndexOf(focusedContent->GetBindingParent());
  }
  RefPtr<Element> element;
  nsIFrame* frame;
  int32_t length = mAccessKeys.Count();
  for (uint32_t i = 0; i < aAccessCharCodes.Length(); ++i) {
    uint32_t ch = aAccessCharCodes[i];
    nsAutoString accessKey;
    AppendUCS4ToUTF16(ch, accessKey);
    for (count = 1; count <= length; ++count) {
      // mAccessKeys always stores Element instances.
      element = mAccessKeys[(start + count) % length]->AsElement();
      frame = element->GetPrimaryFrame();
      if (IsAccessKeyTarget(element, frame, accessKey)) {
        if (!aExecute) {
          return true;
        }
        bool shouldActivate = Prefs::KeyCausesActivation();

        if (aIsRepeat && nsContentUtils::IsChromeDoc(element->OwnerDoc())) {
          shouldActivate = false;
        }

        while (shouldActivate && ++count <= length) {
          nsIContent* oc = mAccessKeys[(start + count) % length];
          nsIFrame* of = oc->GetPrimaryFrame();
          if (IsAccessKeyTarget(oc, of, accessKey)) shouldActivate = false;
        }

        bool focusChanged = false;
        if (shouldActivate) {
          focusChanged =
              element->PerformAccesskey(shouldActivate, aIsTrustedEvent);
        } else {
          nsIFocusManager* fm = nsFocusManager::GetFocusManager();
          if (fm) {
            fm->SetFocus(element, nsIFocusManager::FLAG_BYKEY);
            focusChanged = true;
          }
        }

        if (focusChanged && aIsTrustedEvent) {
          // If this is a child process, inform the parent that we want the
          // focus, but pass false since we don't want to change the window
          // order.
          nsIDocShell* docShell = mPresContext->GetDocShell();
          nsCOMPtr<nsITabChild> child =
              docShell ? docShell->GetTabChild() : nullptr;
          if (child) {
            child->SendRequestFocus(false);
          }
        }

        return true;
      }
    }
  }
  return false;
}

// static
void EventStateManager::GetAccessKeyLabelPrefix(Element* aElement,
                                                nsAString& aPrefix) {
  aPrefix.Truncate();
  nsAutoString separator, modifierText;
  nsContentUtils::GetModifierSeparatorText(separator);

  AccessKeyType accessKeyType =
      GetAccessKeyTypeFor(aElement->OwnerDoc()->GetDocShell());
  if (accessKeyType == AccessKeyType::eNone) {
    return;
  }
  Modifiers modifiers = WidgetKeyboardEvent::AccessKeyModifiers(accessKeyType);
  if (modifiers == MODIFIER_NONE) {
    return;
  }

  if (modifiers & MODIFIER_CONTROL) {
    nsContentUtils::GetControlText(modifierText);
    aPrefix.Append(modifierText + separator);
  }
  if (modifiers & MODIFIER_META) {
    nsContentUtils::GetMetaText(modifierText);
    aPrefix.Append(modifierText + separator);
  }
  if (modifiers & MODIFIER_OS) {
    nsContentUtils::GetOSText(modifierText);
    aPrefix.Append(modifierText + separator);
  }
  if (modifiers & MODIFIER_ALT) {
    nsContentUtils::GetAltText(modifierText);
    aPrefix.Append(modifierText + separator);
  }
  if (modifiers & MODIFIER_SHIFT) {
    nsContentUtils::GetShiftText(modifierText);
    aPrefix.Append(modifierText + separator);
  }
}

struct MOZ_STACK_CLASS AccessKeyInfo {
  WidgetKeyboardEvent* event;
  nsTArray<uint32_t>& charCodes;

  AccessKeyInfo(WidgetKeyboardEvent* aEvent, nsTArray<uint32_t>& aCharCodes)
      : event(aEvent), charCodes(aCharCodes) {}
};

static bool HandleAccessKeyInRemoteChild(TabParent* aTabParent, void* aArg) {
  AccessKeyInfo* accessKeyInfo = static_cast<AccessKeyInfo*>(aArg);

  // Only forward accesskeys for the active tab.
  bool active;
  aTabParent->GetDocShellIsActive(&active);
  if (active) {
    // Even if there is no target for the accesskey in this process,
    // the event may match with a content accesskey.  If so, the keyboard
    // event should be handled with reply event for preventing double action.
    // (e.g., Alt+Shift+F on Windows may focus a content in remote and open
    // "File" menu.)
    accessKeyInfo->event->StopPropagation();
    accessKeyInfo->event->MarkAsWaitingReplyFromRemoteProcess();
    aTabParent->HandleAccessKey(*accessKeyInfo->event,
                                accessKeyInfo->charCodes);
    return true;
  }

  return false;
}

bool EventStateManager::WalkESMTreeToHandleAccessKey(
    WidgetKeyboardEvent* aEvent, nsPresContext* aPresContext,
    nsTArray<uint32_t>& aAccessCharCodes, nsIDocShellTreeItem* aBubbledFrom,
    ProcessingAccessKeyState aAccessKeyState, bool aExecute) {
  EnsureDocument(mPresContext);
  nsCOMPtr<nsIDocShell> docShell = aPresContext->GetDocShell();
  if (NS_WARN_IF(!docShell) || NS_WARN_IF(!mDocument)) {
    return false;
  }
  AccessKeyType accessKeyType = GetAccessKeyTypeFor(docShell);
  if (accessKeyType == AccessKeyType::eNone) {
    return false;
  }
  // Alt or other accesskey modifier is down, we may need to do an accesskey.
  if (mAccessKeys.Count() > 0 &&
      aEvent->ModifiersMatchWithAccessKey(accessKeyType)) {
    // Someone registered an accesskey.  Find and activate it.
    if (LookForAccessKeyAndExecute(aAccessCharCodes, aEvent->IsTrusted(),
                                   aEvent->mIsRepeat, aExecute)) {
      return true;
    }
  }

  int32_t childCount;
  docShell->GetChildCount(&childCount);
  for (int32_t counter = 0; counter < childCount; counter++) {
    // Not processing the child which bubbles up the handling
    nsCOMPtr<nsIDocShellTreeItem> subShellItem;
    docShell->GetChildAt(counter, getter_AddRefs(subShellItem));
    if (aAccessKeyState == eAccessKeyProcessingUp &&
        subShellItem == aBubbledFrom) {
      continue;
    }

    nsCOMPtr<nsIDocShell> subDS = do_QueryInterface(subShellItem);
    if (subDS && IsShellVisible(subDS)) {
      nsCOMPtr<nsIPresShell> subPS = subDS->GetPresShell();

      // Docshells need not have a presshell (eg. display:none
      // iframes, docshells in transition between documents, etc).
      if (!subPS) {
        // Oh, well.  Just move on to the next child
        continue;
      }

      nsPresContext* subPC = subPS->GetPresContext();

      EventStateManager* esm =
          static_cast<EventStateManager*>(subPC->EventStateManager());

      if (esm && esm->WalkESMTreeToHandleAccessKey(
                     aEvent, subPC, aAccessCharCodes, nullptr,
                     eAccessKeyProcessingDown, aExecute)) {
        return true;
      }
    }
  }  // if end . checking all sub docshell ends here.

  // bubble up the process to the parent docshell if necessary
  if (eAccessKeyProcessingDown != aAccessKeyState) {
    nsCOMPtr<nsIDocShellTreeItem> parentShellItem;
    docShell->GetParent(getter_AddRefs(parentShellItem));
    nsCOMPtr<nsIDocShell> parentDS = do_QueryInterface(parentShellItem);
    if (parentDS) {
      nsCOMPtr<nsIPresShell> parentPS = parentDS->GetPresShell();
      NS_ASSERTION(parentPS, "Our PresShell exists but the parent's does not?");

      nsPresContext* parentPC = parentPS->GetPresContext();
      NS_ASSERTION(parentPC, "PresShell without PresContext");

      EventStateManager* esm =
          static_cast<EventStateManager*>(parentPC->EventStateManager());
      if (esm && esm->WalkESMTreeToHandleAccessKey(
                     aEvent, parentPC, aAccessCharCodes, docShell,
                     eAccessKeyProcessingDown, aExecute)) {
        return true;
      }
    }
  }  // if end. bubble up process

  // If the content access key modifier is pressed, try remote children
  if (aExecute &&
      aEvent->ModifiersMatchWithAccessKey(AccessKeyType::eContent) &&
      mDocument && mDocument->GetWindow()) {
    // If the focus is currently on a node with a TabParent, the key event
    // should've gotten forwarded to the child process and HandleAccessKey
    // called from there.
    if (TabParent::GetFrom(GetFocusedContent())) {
      // If access key may be only in remote contents, this method won't handle
      // access key synchronously.  In this case, only reply event should reach
      // here.
      MOZ_ASSERT(aEvent->IsHandledInRemoteProcess() ||
                 !aEvent->IsWaitingReplyFromRemoteProcess());
    }
    // If focus is somewhere else, then we need to check the remote children.
    // However, if the event has already been handled in a remote process,
    // then, focus is moved from the remote process after posting the event.
    // In such case, we shouldn't retry to handle access keys in remote
    // processes.
    else if (!aEvent->IsHandledInRemoteProcess()) {
      AccessKeyInfo accessKeyInfo(aEvent, aAccessCharCodes);
      nsContentUtils::CallOnAllRemoteChildren(
          mDocument->GetWindow(), HandleAccessKeyInRemoteChild, &accessKeyInfo);
    }
  }

  return false;
}  // end of HandleAccessKey

void EventStateManager::DispatchCrossProcessEvent(WidgetEvent* aEvent,
                                                  nsFrameLoader* aFrameLoader,
                                                  nsEventStatus* aStatus) {
  TabParent* remote = TabParent::GetFrom(aFrameLoader);
  if (!remote) {
    return;
  }

  if (aEvent->mLayersId.IsValid()) {
    TabParent* preciseRemote =
        TabParent::GetTabParentFromLayersId(aEvent->mLayersId);
    if (preciseRemote) {
      remote = preciseRemote;
    }
    // else there is a race between APZ and the LayersId to TabParent mapping,
    // so fall back to delivering the event to the topmost child process.
  }
  // else if aEvent->mLayersId was not valid: APZ thinks a pointer
  // event didn't hit anything but traditional targeting believed it
  // belongs to a child process-backed frame loader. Dispatch to the
  // top-level content process found by traditional targeting.

  switch (aEvent->mClass) {
    case eMouseEventClass: {
      remote->SendRealMouseEvent(*aEvent->AsMouseEvent());
      return;
    }
    case eKeyboardEventClass: {
      remote->SendRealKeyEvent(*aEvent->AsKeyboardEvent());
      return;
    }
    case eWheelEventClass: {
      remote->SendMouseWheelEvent(*aEvent->AsWheelEvent());
      return;
    }
    case eTouchEventClass: {
      // Let the child process synthesize a mouse event if needed, and
      // ensure we don't synthesize one in this process.
      *aStatus = nsEventStatus_eConsumeNoDefault;
      remote->SendRealTouchEvent(*aEvent->AsTouchEvent());
      return;
    }
    case eDragEventClass: {
      RefPtr<TabParent> tabParent = remote;
      tabParent->Manager()->MaybeInvokeDragSession(tabParent);

      nsCOMPtr<nsIDragSession> dragSession = nsContentUtils::GetDragSession();
      uint32_t dropEffect = nsIDragService::DRAGDROP_ACTION_NONE;
      uint32_t action = nsIDragService::DRAGDROP_ACTION_NONE;
      nsCOMPtr<nsIPrincipal> principal;
      if (dragSession) {
        dragSession->DragEventDispatchedToChildProcess();
        dragSession->GetDragAction(&action);
        dragSession->GetTriggeringPrincipal(getter_AddRefs(principal));
        RefPtr<DataTransfer> initialDataTransfer =
            dragSession->GetDataTransfer();
        if (initialDataTransfer) {
          dropEffect = initialDataTransfer->DropEffectInt();
        }
      }

      tabParent->SendRealDragEvent(*aEvent->AsDragEvent(), action, dropEffect,
                                   IPC::Principal(principal));
      return;
    }
    case ePluginEventClass: {
      *aStatus = nsEventStatus_eConsumeNoDefault;
      remote->SendPluginEvent(*aEvent->AsPluginEvent());
      return;
    }
    default: { MOZ_CRASH("Attempt to send non-whitelisted event?"); }
  }
}

bool EventStateManager::IsRemoteTarget(nsIContent* target) {
  return !!TabParent::GetFrom(target);
}

bool EventStateManager::HandleCrossProcessEvent(WidgetEvent* aEvent,
                                                nsEventStatus* aStatus) {
  if (!aEvent->CanBeSentToRemoteProcess()) {
    return false;
  }

  MOZ_ASSERT(!aEvent->HasBeenPostedToRemoteProcess(),
             "Why do we need to post same event to remote processes again?");

  // Collect the remote event targets we're going to forward this
  // event to.
  //
  // NB: the elements of |targets| must be unique, for correctness.
  AutoTArray<nsCOMPtr<nsIContent>, 1> targets;
  if (aEvent->mClass != eTouchEventClass || aEvent->mMessage == eTouchStart) {
    // If this event only has one target, and it's remote, add it to
    // the array.
    nsIFrame* frame = aEvent->mMessage == eDragExit
                          ? sLastDragOverFrame.GetFrame()
                          : GetEventTarget();
    nsIContent* target = frame ? frame->GetContent() : nullptr;
    if (IsRemoteTarget(target)) {
      targets.AppendElement(target);
    }
  } else {
    // This is a touch event with possibly multiple touch points.
    // Each touch point may have its own target.  So iterate through
    // all of them and collect the unique set of targets for event
    // forwarding.
    //
    // This loop is similar to the one used in
    // PresShell::DispatchTouchEvent().
    const WidgetTouchEvent::TouchArray& touches =
        aEvent->AsTouchEvent()->mTouches;
    for (uint32_t i = 0; i < touches.Length(); ++i) {
      Touch* touch = touches[i];
      // NB: the |mChanged| check is an optimization, subprocesses can
      // compute this for themselves.  If the touch hasn't changed, we
      // may be able to avoid forwarding the event entirely (which is
      // not free).
      if (!touch || !touch->mChanged) {
        continue;
      }
      nsCOMPtr<EventTarget> targetPtr = touch->mTarget;
      if (!targetPtr) {
        continue;
      }
      nsCOMPtr<nsIContent> target = do_QueryInterface(targetPtr);
      if (IsRemoteTarget(target) && !targets.Contains(target)) {
        targets.AppendElement(target);
      }
    }
  }

  if (targets.Length() == 0) {
    return false;
  }

  // Look up the frame loader for all the remote targets we found, and
  // then dispatch the event to the remote content they represent.
  for (uint32_t i = 0; i < targets.Length(); ++i) {
    nsIContent* target = targets[i];
    RefPtr<nsFrameLoaderOwner> loaderOwner = do_QueryObject(target);
    if (!loaderOwner) {
      continue;
    }

    RefPtr<nsFrameLoader> frameLoader = loaderOwner->GetFrameLoader();
    if (!frameLoader) {
      continue;
    }

    DispatchCrossProcessEvent(aEvent, frameLoader, aStatus);
  }
  return aEvent->HasBeenPostedToRemoteProcess();
}

//
// CreateClickHoldTimer
//
// Fire off a timer for determining if the user wants click-hold. This timer
// is a one-shot that will be cancelled when the user moves enough to fire
// a drag.
//
void EventStateManager::CreateClickHoldTimer(nsPresContext* inPresContext,
                                             nsIFrame* inDownFrame,
                                             WidgetGUIEvent* inMouseDownEvent) {
  if (!inMouseDownEvent->IsTrusted() || IsRemoteTarget(mGestureDownContent) ||
      sIsPointerLocked) {
    return;
  }

  // just to be anal (er, safe)
  if (mClickHoldTimer) {
    mClickHoldTimer->Cancel();
    mClickHoldTimer = nullptr;
  }

  // if content clicked on has a popup, don't even start the timer
  // since we'll end up conflicting and both will show.
  if (mGestureDownContent &&
      nsContentUtils::HasNonEmptyAttr(mGestureDownContent, kNameSpaceID_None,
                                      nsGkAtoms::popup)) {
    return;
  }

  int32_t clickHoldDelay =
      Preferences::GetInt("ui.click_hold_context_menus.delay", 500);
  NS_NewTimerWithFuncCallback(
      getter_AddRefs(mClickHoldTimer), sClickHoldCallback, this, clickHoldDelay,
      nsITimer::TYPE_ONE_SHOT, "EventStateManager::CreateClickHoldTimer",
      SystemGroup::EventTargetFor(TaskCategory::Other));
}  // CreateClickHoldTimer

//
// KillClickHoldTimer
//
// Stop the timer that would show the context menu dead in its tracks
//
void EventStateManager::KillClickHoldTimer() {
  if (mClickHoldTimer) {
    mClickHoldTimer->Cancel();
    mClickHoldTimer = nullptr;
  }
}

//
// sClickHoldCallback
//
// This fires after the mouse has been down for a certain length of time.
//
void EventStateManager::sClickHoldCallback(nsITimer* aTimer, void* aESM) {
  RefPtr<EventStateManager> self = static_cast<EventStateManager*>(aESM);
  if (self) {
    self->FireContextClick();
  }

  // NOTE: |aTimer| and |self->mAutoHideTimer| are invalid after calling
  // ClosePopup();

}  // sAutoHideCallback

//
// FireContextClick
//
// If we're this far, our timer has fired, which means the mouse has been down
// for a certain period of time and has not moved enough to generate a
// dragGesture. We can be certain the user wants a context-click at this stage,
// so generate a dom event and fire it in.
//
// After the event fires, check if PreventDefault() has been set on the event
// which means that someone either ate the event or put up a context menu. This
// is our cue to stop tracking the drag gesture. If we always did this,
// draggable items w/out a context menu wouldn't be draggable after a certain
// length of time, which is _not_ what we want.
//
void EventStateManager::FireContextClick() {
  if (!mGestureDownContent || !mPresContext || sIsPointerLocked) {
    return;
  }

#ifdef XP_MACOSX
  // Hack to ensure that we don't show a context menu when the user
  // let go of the mouse after a long cpu-hogging operation prevented
  // us from handling any OS events. See bug 117589.
  if (!CGEventSourceButtonState(kCGEventSourceStateCombinedSessionState,
                                kCGMouseButtonLeft))
    return;
#endif

  nsEventStatus status = nsEventStatus_eIgnore;

  // Dispatch to the DOM. We have to fake out the ESM and tell it that the
  // current target frame is actually where the mouseDown occurred, otherwise it
  // will use the frame the mouse is currently over which may or may not be
  // the same. (Note: saari and I have decided that we don't have to reset
  // |mCurrentTarget| when we're through because no one else is doing anything
  // more with this event and it will get reset on the very next event to the
  // correct frame).
  mCurrentTarget = mPresContext->GetPrimaryFrameFor(mGestureDownContent);
  // make sure the widget sticks around
  nsCOMPtr<nsIWidget> targetWidget;
  if (mCurrentTarget && (targetWidget = mCurrentTarget->GetNearestWidget())) {
    NS_ASSERTION(
        mPresContext == mCurrentTarget->PresContext(),
        "a prescontext returned a primary frame that didn't belong to it?");

    // before dispatching, check that we're not on something that
    // doesn't get a context menu
    bool allowedToDispatch = true;

    if (mGestureDownContent->IsAnyOfXULElements(nsGkAtoms::scrollbar,
                                                nsGkAtoms::scrollbarbutton,
                                                nsGkAtoms::button)) {
      allowedToDispatch = false;
    } else if (mGestureDownContent->IsXULElement(nsGkAtoms::toolbarbutton)) {
      // a <toolbarbutton> that has the container attribute set
      // will already have its own dropdown.
      if (nsContentUtils::HasNonEmptyAttr(
              mGestureDownContent, kNameSpaceID_None, nsGkAtoms::container)) {
        allowedToDispatch = false;
      } else {
        // If the toolbar button has an open menu, don't attempt to open
        // a second menu
        if (mGestureDownContent->IsElement() &&
            mGestureDownContent->AsElement()->AttrValueIs(
                kNameSpaceID_None, nsGkAtoms::open, nsGkAtoms::_true,
                eCaseMatters)) {
          allowedToDispatch = false;
        }
      }
    } else if (mGestureDownContent->IsHTMLElement()) {
      nsCOMPtr<nsIFormControl> formCtrl(do_QueryInterface(mGestureDownContent));

      if (formCtrl) {
        allowedToDispatch =
            formCtrl->IsTextOrNumberControl(/*aExcludePassword*/ false) ||
            formCtrl->ControlType() == NS_FORM_INPUT_FILE;
      } else if (mGestureDownContent->IsAnyOfHTMLElements(
                     nsGkAtoms::embed, nsGkAtoms::object, nsGkAtoms::label)) {
        allowedToDispatch = false;
      }
    }

    if (allowedToDispatch) {
      // init the event while mCurrentTarget is still good
      WidgetMouseEvent event(true, eContextMenu, targetWidget,
                             WidgetMouseEvent::eReal);
      event.mClickCount = 1;
      FillInEventFromGestureDown(&event);

      // stop selection tracking, we're in control now
      if (mCurrentTarget) {
        RefPtr<nsFrameSelection> frameSel = mCurrentTarget->GetFrameSelection();

        if (frameSel && frameSel->GetDragState()) {
          // note that this can cause selection changed events to fire if we're
          // in a text field, which will null out mCurrentTarget
          frameSel->SetDragState(false);
        }
      }

      Document* doc = mGestureDownContent->GetComposedDoc();
      AutoHandlingUserInputStatePusher userInpStatePusher(true, &event, doc);

      // dispatch to DOM
      EventDispatcher::Dispatch(mGestureDownContent, mPresContext, &event,
                                nullptr, &status);

      // We don't need to dispatch to frame handling because no frames
      // watch eContextMenu except for nsMenuFrame and that's only for
      // dismissal. That's just as well since we don't really know
      // which frame to send it to.
    }
  }

  // now check if the event has been handled. If so, stop tracking a drag
  if (status == nsEventStatus_eConsumeNoDefault) {
    StopTrackingDragGesture();
  }

  KillClickHoldTimer();

}  // FireContextClick

//
// BeginTrackingDragGesture
//
// Record that the mouse has gone down and that we should move to TRACKING state
// of d&d gesture tracker.
//
// We also use this to track click-hold context menus. When the mouse goes down,
// fire off a short timer. If the timer goes off and we have yet to fire the
// drag gesture (ie, the mouse hasn't moved a certain distance), then we can
// assume the user wants a click-hold, so fire a context-click event. We only
// want to cancel the drag gesture if the context-click event is handled.
//
void EventStateManager::BeginTrackingDragGesture(nsPresContext* aPresContext,
                                                 WidgetMouseEvent* inDownEvent,
                                                 nsIFrame* inDownFrame) {
  if (!inDownEvent->mWidget) {
    return;
  }

  // Note that |inDownEvent| could be either a mouse down event or a
  // synthesized mouse move event.
  SetGestureDownPoint(inDownEvent);

  if (inDownFrame) {
    inDownFrame->GetContentForEvent(inDownEvent,
                                    getter_AddRefs(mGestureDownContent));

    mGestureDownFrameOwner = inDownFrame->GetContent();
    if (!mGestureDownFrameOwner) {
      mGestureDownFrameOwner = mGestureDownContent;
    }
  }
  mGestureModifiers = inDownEvent->mModifiers;
  mGestureDownButtons = inDownEvent->buttons;

  if (inDownEvent->mMessage != eMouseTouchDrag &&
      Prefs::ClickHoldContextMenu()) {
    // fire off a timer to track click-hold
    CreateClickHoldTimer(aPresContext, inDownFrame, inDownEvent);
  }
}

void EventStateManager::SetGestureDownPoint(WidgetGUIEvent* aEvent) {
  mGestureDownPoint =
      GetEventRefPoint(aEvent) + aEvent->mWidget->WidgetToScreenOffset();
}

LayoutDeviceIntPoint EventStateManager::GetEventRefPoint(
    WidgetEvent* aEvent) const {
  auto touchEvent = aEvent->AsTouchEvent();
  return (touchEvent && !touchEvent->mTouches.IsEmpty())
             ? aEvent->AsTouchEvent()->mTouches[0]->mRefPoint
             : aEvent->mRefPoint;
}

void EventStateManager::BeginTrackingRemoteDragGesture(nsIContent* aContent) {
  mGestureDownContent = aContent;
  mGestureDownFrameOwner = aContent;
}

//
// StopTrackingDragGesture
//
// Record that the mouse has gone back up so that we should leave the TRACKING
// state of d&d gesture tracker and return to the START state.
//
void EventStateManager::StopTrackingDragGesture() {
  mGestureDownContent = nullptr;
  mGestureDownFrameOwner = nullptr;
}

void EventStateManager::FillInEventFromGestureDown(WidgetMouseEvent* aEvent) {
  NS_ASSERTION(aEvent->mWidget == mCurrentTarget->GetNearestWidget(),
               "Incorrect widget in event");

  // Set the coordinates in the new event to the coordinates of
  // the old event, adjusted for the fact that the widget might be
  // different
  aEvent->mRefPoint =
      mGestureDownPoint - aEvent->mWidget->WidgetToScreenOffset();
  aEvent->mModifiers = mGestureModifiers;
  aEvent->buttons = mGestureDownButtons;
}

void EventStateManager::MaybeFirePointerCancel(WidgetInputEvent* aEvent) {
  nsCOMPtr<nsIPresShell> shell = mPresContext->GetPresShell();
  AutoWeakFrame targetFrame = mCurrentTarget;

  if (!PointerEventHandler::IsPointerEventEnabled() || !shell || !targetFrame) {
    return;
  }

  nsCOMPtr<nsIContent> content;
  targetFrame->GetContentForEvent(aEvent, getter_AddRefs(content));
  if (!content) {
    return;
  }

  nsEventStatus status = nsEventStatus_eIgnore;

  if (WidgetMouseEvent* aMouseEvent = aEvent->AsMouseEvent()) {
    WidgetPointerEvent event(*aMouseEvent);
    PointerEventHandler::InitPointerEventFromMouse(&event, aMouseEvent,
                                                   ePointerCancel);

    event.convertToPointer = false;
    shell->HandleEventWithTarget(&event, targetFrame, content, &status);
  } else if (WidgetTouchEvent* aTouchEvent = aEvent->AsTouchEvent()) {
    WidgetPointerEvent event(aTouchEvent->IsTrusted(), ePointerCancel,
                             aTouchEvent->mWidget);

    PointerEventHandler::InitPointerEventFromTouch(
        &event, aTouchEvent, aTouchEvent->mTouches[0], true);

    event.convertToPointer = false;
    shell->HandleEventWithTarget(&event, targetFrame, content, &status);
  } else {
    MOZ_ASSERT(false);
  }

  // HandleEventWithTarget clears out mCurrentTarget, which may be used in the
  // caller GenerateDragGesture. We have to restore mCurrentTarget.
  mCurrentTarget = targetFrame;
}

bool EventStateManager::IsEventOutsideDragThreshold(
    WidgetInputEvent* aEvent) const {
  static int32_t sPixelThresholdX = 0;
  static int32_t sPixelThresholdY = 0;

  if (!sPixelThresholdX) {
    sPixelThresholdX =
        LookAndFeel::GetInt(LookAndFeel::eIntID_DragThresholdX, 0);
    sPixelThresholdY =
        LookAndFeel::GetInt(LookAndFeel::eIntID_DragThresholdY, 0);
    if (!sPixelThresholdX) sPixelThresholdX = 5;
    if (!sPixelThresholdY) sPixelThresholdY = 5;
  }

  LayoutDeviceIntPoint pt =
      aEvent->mWidget->WidgetToScreenOffset() + GetEventRefPoint(aEvent);
  LayoutDeviceIntPoint distance = pt - mGestureDownPoint;
  return Abs(distance.x) > AssertedCast<uint32_t>(sPixelThresholdX) ||
         Abs(distance.y) > AssertedCast<uint32_t>(sPixelThresholdY);
}

//
// GenerateDragGesture
//
// If we're in the TRACKING state of the d&d gesture tracker, check the current
// position of the mouse in relation to the old one. If we've moved a sufficient
// amount from the mouse down, then fire off a drag gesture event.
void EventStateManager::GenerateDragGesture(nsPresContext* aPresContext,
                                            WidgetInputEvent* aEvent) {
  NS_ASSERTION(aPresContext, "This shouldn't happen.");
  if (IsTrackingDragGesture()) {
    mCurrentTarget = mGestureDownFrameOwner->GetPrimaryFrame();

    if (!mCurrentTarget || !mCurrentTarget->GetNearestWidget()) {
      StopTrackingDragGesture();
      return;
    }

    // Check if selection is tracking drag gestures, if so
    // don't interfere!
    if (mCurrentTarget) {
      RefPtr<nsFrameSelection> frameSel = mCurrentTarget->GetFrameSelection();
      if (frameSel && frameSel->GetDragState()) {
        StopTrackingDragGesture();
        return;
      }
    }

    // If non-native code is capturing the mouse don't start a drag.
    if (nsIPresShell::IsMouseCapturePreventingDrag()) {
      StopTrackingDragGesture();
      return;
    }

    if (IsEventOutsideDragThreshold(aEvent)) {
      if (Prefs::ClickHoldContextMenu()) {
        // stop the click-hold before we fire off the drag gesture, in case
        // it takes a long time
        KillClickHoldTimer();
      }

      nsCOMPtr<nsIDocShell> docshell = aPresContext->GetDocShell();
      if (!docshell) {
        return;
      }

      nsCOMPtr<nsPIDOMWindowOuter> window = docshell->GetWindow();
      if (!window) return;

      RefPtr<DataTransfer> dataTransfer =
          new DataTransfer(window, eDragStart, false, -1);
      auto protectDataTransfer = MakeScopeExit([&] {
        if (dataTransfer) {
          dataTransfer->Disconnect();
        }
      });

      RefPtr<Selection> selection;
      nsCOMPtr<nsIContent> eventContent, targetContent;
      nsCOMPtr<nsIPrincipal> principal;
      mCurrentTarget->GetContentForEvent(aEvent, getter_AddRefs(eventContent));
      if (eventContent)
        DetermineDragTargetAndDefaultData(
            window, eventContent, dataTransfer, getter_AddRefs(selection),
            getter_AddRefs(targetContent), getter_AddRefs(principal));

      // Stop tracking the drag gesture now. This should stop us from
      // reentering GenerateDragGesture inside DOM event processing.
      StopTrackingDragGesture();

      if (!targetContent) return;

      // Use our targetContent, now that we've determined it, as the
      // parent object of the DataTransfer.
      nsCOMPtr<nsIContent> parentContent =
          targetContent->FindFirstNonChromeOnlyAccessContent();
      dataTransfer->SetParentObject(parentContent);

      sLastDragOverFrame = nullptr;
      nsCOMPtr<nsIWidget> widget = mCurrentTarget->GetNearestWidget();

      // get the widget from the target frame
      WidgetDragEvent startEvent(aEvent->IsTrusted(), eDragStart, widget);
      FillInEventFromGestureDown(&startEvent);

      startEvent.mDataTransfer = dataTransfer;
      if (aEvent->AsMouseEvent()) {
        startEvent.inputSource = aEvent->AsMouseEvent()->inputSource;
      } else if (aEvent->AsTouchEvent()) {
        startEvent.inputSource = MouseEvent_Binding::MOZ_SOURCE_TOUCH;
      } else {
        MOZ_ASSERT(false);
      }

      // Dispatch to the DOM. By setting mCurrentTarget we are faking
      // out the ESM and telling it that the current target frame is
      // actually where the mouseDown occurred, otherwise it will use
      // the frame the mouse is currently over which may or may not be
      // the same. (Note: saari and I have decided that we don't have
      // to reset |mCurrentTarget| when we're through because no one
      // else is doing anything more with this event and it will get
      // reset on the very next event to the correct frame).

      // Hold onto old target content through the event and reset after.
      nsCOMPtr<nsIContent> targetBeforeEvent = mCurrentTargetContent;

      // Set the current target to the content for the mouse down
      mCurrentTargetContent = targetContent;

      // Dispatch the dragstart event to the DOM.
      nsEventStatus status = nsEventStatus_eIgnore;
      EventDispatcher::Dispatch(targetContent, aPresContext, &startEvent,
                                nullptr, &status);

      WidgetDragEvent* event = &startEvent;

      nsCOMPtr<nsIObserverService> observerService =
          mozilla::services::GetObserverService();
      // Emit observer event to allow addons to modify the DataTransfer object.
      if (observerService) {
        observerService->NotifyObservers(dataTransfer,
                                         "on-datatransfer-available", nullptr);
      }

      if (status != nsEventStatus_eConsumeNoDefault) {
        bool dragStarted =
            DoDefaultDragStart(aPresContext, event, dataTransfer, targetContent,
                               selection, principal);
        if (dragStarted) {
          sActiveESM = nullptr;
          MaybeFirePointerCancel(aEvent);
          aEvent->StopPropagation();
        }
      }

      // Reset mCurretTargetContent to what it was
      mCurrentTargetContent = targetBeforeEvent;
    }

    // Now flush all pending notifications, for better responsiveness
    // while dragging.
    FlushPendingEvents(aPresContext);
  }
}  // GenerateDragGesture

void EventStateManager::DetermineDragTargetAndDefaultData(
    nsPIDOMWindowOuter* aWindow, nsIContent* aSelectionTarget,
    DataTransfer* aDataTransfer, Selection** aSelection,
    nsIContent** aTargetNode, nsIPrincipal** aPrincipal) {
  *aTargetNode = nullptr;

  // GetDragData determines if a selection, link or image in the content
  // should be dragged, and places the data associated with the drag in the
  // data transfer.
  // mGestureDownContent is the node where the mousedown event for the drag
  // occurred, and aSelectionTarget is the node to use when a selection is used
  bool canDrag;
  nsCOMPtr<nsIContent> dragDataNode;
  bool wasAlt = (mGestureModifiers & MODIFIER_ALT) != 0;
  nsresult rv = nsContentAreaDragDrop::GetDragData(
      aWindow, mGestureDownContent, aSelectionTarget, wasAlt, aDataTransfer,
      &canDrag, aSelection, getter_AddRefs(dragDataNode), aPrincipal);
  if (NS_FAILED(rv) || !canDrag) return;

  // if GetDragData returned a node, use that as the node being dragged.
  // Otherwise, if a selection is being dragged, use the node within the
  // selection that was dragged. Otherwise, just use the mousedown target.
  nsIContent* dragContent = mGestureDownContent;
  if (dragDataNode)
    dragContent = dragDataNode;
  else if (*aSelection)
    dragContent = aSelectionTarget;

  nsIContent* originalDragContent = dragContent;

  // If a selection isn't being dragged, look for an ancestor with the
  // draggable property set. If one is found, use that as the target of the
  // drag instead of the node that was clicked on. If a draggable node wasn't
  // found, just use the clicked node.
  if (!*aSelection) {
    while (dragContent) {
      if (auto htmlElement = nsGenericHTMLElement::FromNode(dragContent)) {
        if (htmlElement->Draggable()) {
          break;
        }
      } else {
        if (dragContent->IsXULElement()) {
          // All XUL elements are draggable, so if a XUL element is
          // encountered, stop looking for draggable nodes and just use the
          // original clicked node instead.
          // XXXndeakin
          // In the future, we will want to improve this so that XUL has a
          // better way to specify whether something is draggable than just
          // on/off.
          dragContent = mGestureDownContent;
          break;
        }
        // otherwise, it's not an HTML or XUL element, so just keep looking
      }
      dragContent = dragContent->GetFlattenedTreeParent();
    }
  }

  // if no node in the hierarchy was found to drag, but the GetDragData method
  // returned a node, use that returned node. Otherwise, nothing is draggable.
  if (!dragContent && dragDataNode) dragContent = dragDataNode;

  if (dragContent) {
    // if an ancestor node was used instead, clear the drag data
    // XXXndeakin rework this a bit. Find a way to just not call GetDragData if
    // we don't need to.
    if (dragContent != originalDragContent) aDataTransfer->ClearAll();
    *aTargetNode = dragContent;
    NS_ADDREF(*aTargetNode);
  }
}

bool EventStateManager::DoDefaultDragStart(nsPresContext* aPresContext,
                                           WidgetDragEvent* aDragEvent,
                                           DataTransfer* aDataTransfer,
                                           nsIContent* aDragTarget,
                                           Selection* aSelection,
                                           nsIPrincipal* aPrincipal) {
  nsCOMPtr<nsIDragService> dragService =
      do_GetService("@mozilla.org/widget/dragservice;1");
  if (!dragService) return false;

  // Default handling for the dragstart event.
  //
  // First, check if a drag session already exists. This means that the drag
  // service was called directly within a draggesture handler. In this case,
  // don't do anything more, as it is assumed that the handler is managing
  // drag and drop manually. Make sure to return true to indicate that a drag
  // began.
  nsCOMPtr<nsIDragSession> dragSession;
  dragService->GetCurrentSession(getter_AddRefs(dragSession));
  if (dragSession) return true;

  // No drag session is currently active, so check if a handler added
  // any items to be dragged. If not, there isn't anything to drag.
  uint32_t count = 0;
  if (aDataTransfer) {
    count = aDataTransfer->MozItemCount();
  }
  if (!count) {
    return false;
  }

  // Get the target being dragged, which may not be the same as the
  // target of the mouse event. If one wasn't set in the
  // aDataTransfer during the event handler, just use the original
  // target instead.
  nsCOMPtr<nsIContent> dragTarget = aDataTransfer->GetDragTarget();
  if (!dragTarget) {
    dragTarget = aDragTarget;
    if (!dragTarget) return false;
  }

  // check which drag effect should initially be used. If the effect was not
  // set, just use all actions, otherwise Windows won't allow a drop.
  uint32_t action = aDataTransfer->EffectAllowedInt();
  if (action == nsIDragService::DRAGDROP_ACTION_UNINITIALIZED)
    action = nsIDragService::DRAGDROP_ACTION_COPY |
             nsIDragService::DRAGDROP_ACTION_MOVE |
             nsIDragService::DRAGDROP_ACTION_LINK;

  // get any custom drag image that was set
  int32_t imageX, imageY;
  Element* dragImage = aDataTransfer->GetDragImage(&imageX, &imageY);

  nsCOMPtr<nsIArray> transArray = aDataTransfer->GetTransferables(dragTarget);
  if (!transArray) return false;

  // After this function returns, the DataTransfer will be cleared so it appears
  // empty to content. We need to pass a DataTransfer into the Drag Session, so
  // we need to make a copy.
  RefPtr<DataTransfer> dataTransfer;
  aDataTransfer->Clone(aDragTarget, eDrop, aDataTransfer->MozUserCancelled(),
                       false, getter_AddRefs(dataTransfer));

  // Copy over the drop effect, as Clone doesn't copy it for us.
  dataTransfer->SetDropEffectInt(aDataTransfer->DropEffectInt());

  // XXXndeakin don't really want to create a new drag DOM event
  // here, but we need something to pass to the InvokeDragSession
  // methods.
  RefPtr<DragEvent> event =
      NS_NewDOMDragEvent(dragTarget, aPresContext, aDragEvent);

  // Use InvokeDragSessionWithSelection if a selection is being dragged,
  // such that the image can be generated from the selected text. However,
  // use InvokeDragSessionWithImage if a custom image was set or something
  // other than a selection is being dragged.
  if (!dragImage && aSelection) {
    dragService->InvokeDragSessionWithSelection(
        aSelection, aPrincipal, transArray, action, event, dataTransfer);
  } else {
    dragService->InvokeDragSessionWithImage(dragTarget, aPrincipal, transArray,
                                            action, dragImage, imageX, imageY,
                                            event, dataTransfer);
  }

  return true;
}

nsresult EventStateManager::GetContentViewer(nsIContentViewer** aCv) {
  *aCv = nullptr;

  nsPIDOMWindowOuter* window = mDocument->GetWindow();
  if (!window) return NS_ERROR_FAILURE;
  nsCOMPtr<nsPIDOMWindowOuter> rootWindow = window->GetPrivateRoot();
  if (!rootWindow) return NS_ERROR_FAILURE;

  TabChild* tabChild = TabChild::GetFrom(rootWindow);
  if (!tabChild) {
    nsIFocusManager* fm = nsFocusManager::GetFocusManager();
    if (!fm) return NS_ERROR_FAILURE;

    nsCOMPtr<mozIDOMWindowProxy> activeWindow;
    fm->GetActiveWindow(getter_AddRefs(activeWindow));
    if (rootWindow != activeWindow) return NS_OK;
  } else {
    if (!tabChild->ParentIsActive()) return NS_OK;
  }

  nsCOMPtr<nsPIDOMWindowOuter> contentWindow =
      nsGlobalWindowOuter::Cast(rootWindow)->GetContent();
  if (!contentWindow) return NS_ERROR_FAILURE;

  Document* doc = contentWindow->GetDoc();
  if (!doc) return NS_ERROR_FAILURE;

  nsCOMPtr<nsISupports> container = doc->GetContainer();
  if (!container) return NS_ERROR_FAILURE;

  nsCOMPtr<nsIDocShell> docshell = do_QueryInterface(container);
  docshell->GetContentViewer(aCv);
  if (!*aCv) return NS_ERROR_FAILURE;

  return NS_OK;
}

nsresult EventStateManager::ChangeTextSize(int32_t change) {
  nsCOMPtr<nsIContentViewer> cv;
  nsresult rv = GetContentViewer(getter_AddRefs(cv));
  NS_ENSURE_SUCCESS(rv, rv);

  if (cv) {
    float textzoom;
    float zoomMin = ((float)Preferences::GetInt("zoom.minPercent", 50)) / 100;
    float zoomMax = ((float)Preferences::GetInt("zoom.maxPercent", 300)) / 100;
    cv->GetTextZoom(&textzoom);
    textzoom += ((float)change) / 10;
    if (textzoom < zoomMin)
      textzoom = zoomMin;
    else if (textzoom > zoomMax)
      textzoom = zoomMax;
    cv->SetTextZoom(textzoom);
  }

  return NS_OK;
}

nsresult EventStateManager::ChangeFullZoom(int32_t change) {
  nsCOMPtr<nsIContentViewer> cv;
  nsresult rv = GetContentViewer(getter_AddRefs(cv));
  NS_ENSURE_SUCCESS(rv, rv);

  if (cv) {
    float fullzoom;
    float zoomMin = ((float)Preferences::GetInt("zoom.minPercent", 50)) / 100;
    float zoomMax = ((float)Preferences::GetInt("zoom.maxPercent", 300)) / 100;
    cv->GetFullZoom(&fullzoom);
    fullzoom += ((float)change) / 10;
    if (fullzoom < zoomMin)
      fullzoom = zoomMin;
    else if (fullzoom > zoomMax)
      fullzoom = zoomMax;
    cv->SetFullZoom(fullzoom);
  }

  return NS_OK;
}

void EventStateManager::DoScrollHistory(int32_t direction) {
  nsCOMPtr<nsISupports> pcContainer(mPresContext->GetContainerWeak());
  if (pcContainer) {
    nsCOMPtr<nsIWebNavigation> webNav(do_QueryInterface(pcContainer));
    if (webNav) {
      // positive direction to go back one step, nonpositive to go forward
      if (direction > 0)
        webNav->GoBack();
      else
        webNav->GoForward();
    }
  }
}

void EventStateManager::DoScrollZoom(nsIFrame* aTargetFrame,
                                     int32_t adjustment) {
  // Exclude form controls and content in chrome docshells.
  nsIContent* content = aTargetFrame->GetContent();
  if (content && !content->IsNodeOfType(nsINode::eHTML_FORM_CONTROL) &&
      !nsContentUtils::IsInChromeDocshell(content->OwnerDoc())) {
    // positive adjustment to decrease zoom, negative to increase
    int32_t change = (adjustment > 0) ? -1 : 1;

    EnsureDocument(mPresContext);
    if (Preferences::GetBool("browser.zoom.full") ||
        content->OwnerDoc()->IsSyntheticDocument()) {
      ChangeFullZoom(change);
    } else {
      ChangeTextSize(change);
    }
    nsContentUtils::DispatchChromeEvent(
        mDocument, ToSupports(mDocument),
        NS_LITERAL_STRING("ZoomChangeUsingMouseWheel"), CanBubble::eYes,
        Cancelable::eYes);
  }
}

static nsIFrame* GetParentFrameToScroll(nsIFrame* aFrame) {
  if (!aFrame) return nullptr;

  if (aFrame->StyleDisplay()->mPosition == NS_STYLE_POSITION_FIXED &&
      nsLayoutUtils::IsReallyFixedPos(aFrame))
    return aFrame->PresContext()->GetPresShell()->GetRootScrollFrame();

  return aFrame->GetParent();
}

void EventStateManager::DispatchLegacyMouseScrollEvents(
    nsIFrame* aTargetFrame, WidgetWheelEvent* aEvent, nsEventStatus* aStatus) {
  MOZ_ASSERT(aEvent);
  MOZ_ASSERT(aStatus);

  if (!aTargetFrame || *aStatus == nsEventStatus_eConsumeNoDefault) {
    return;
  }

  // Ignore mouse wheel transaction for computing legacy mouse wheel
  // events' delta value.
  nsIFrame* scrollFrame = ComputeScrollTargetAndMayAdjustWheelEvent(
      aTargetFrame, aEvent, COMPUTE_LEGACY_MOUSE_SCROLL_EVENT_TARGET);

  nsIScrollableFrame* scrollTarget = do_QueryFrame(scrollFrame);
  nsPresContext* pc =
      scrollFrame ? scrollFrame->PresContext() : aTargetFrame->PresContext();

  // DOM event's delta vales are computed from CSS pixels.
  nsSize scrollAmount = GetScrollAmount(pc, aEvent, scrollTarget);
  nsIntSize scrollAmountInCSSPixels(
      nsPresContext::AppUnitsToIntCSSPixels(scrollAmount.width),
      nsPresContext::AppUnitsToIntCSSPixels(scrollAmount.height));

  // XXX We don't deal with fractional amount in legacy event, though the
  //     default action handler (DoScrollText()) deals with it.
  //     If we implemented such strict computation, we would need additional
  //     accumulated delta values. It would made the code more complicated.
  //     And also it would computes different delta values from older version.
  //     It doesn't make sense to implement such code for legacy events and
  //     rare cases.
  int32_t scrollDeltaX, scrollDeltaY, pixelDeltaX, pixelDeltaY;
  switch (aEvent->mDeltaMode) {
    case WheelEvent_Binding::DOM_DELTA_PAGE:
      scrollDeltaX = !aEvent->mLineOrPageDeltaX
                         ? 0
                         : (aEvent->mLineOrPageDeltaX > 0
                                ? UIEvent_Binding::SCROLL_PAGE_DOWN
                                : UIEvent_Binding::SCROLL_PAGE_UP);
      scrollDeltaY = !aEvent->mLineOrPageDeltaY
                         ? 0
                         : (aEvent->mLineOrPageDeltaY > 0
                                ? UIEvent_Binding::SCROLL_PAGE_DOWN
                                : UIEvent_Binding::SCROLL_PAGE_UP);
      pixelDeltaX = RoundDown(aEvent->mDeltaX * scrollAmountInCSSPixels.width);
      pixelDeltaY = RoundDown(aEvent->mDeltaY * scrollAmountInCSSPixels.height);
      break;

    case WheelEvent_Binding::DOM_DELTA_LINE:
      scrollDeltaX = aEvent->mLineOrPageDeltaX;
      scrollDeltaY = aEvent->mLineOrPageDeltaY;
      pixelDeltaX = RoundDown(aEvent->mDeltaX * scrollAmountInCSSPixels.width);
      pixelDeltaY = RoundDown(aEvent->mDeltaY * scrollAmountInCSSPixels.height);
      break;

    case WheelEvent_Binding::DOM_DELTA_PIXEL:
      scrollDeltaX = aEvent->mLineOrPageDeltaX;
      scrollDeltaY = aEvent->mLineOrPageDeltaY;
      pixelDeltaX = RoundDown(aEvent->mDeltaX);
      pixelDeltaY = RoundDown(aEvent->mDeltaY);
      break;

    default:
      MOZ_CRASH("Invalid deltaMode value comes");
  }

  // Send the legacy events in following order:
  // 1. Vertical scroll
  // 2. Vertical pixel scroll (even if #1 isn't consumed)
  // 3. Horizontal scroll (even if #1 and/or #2 are consumed)
  // 4. Horizontal pixel scroll (even if #3 isn't consumed)

  AutoWeakFrame targetFrame(aTargetFrame);

  MOZ_ASSERT(*aStatus != nsEventStatus_eConsumeNoDefault &&
                 !aEvent->DefaultPrevented(),
             "If you make legacy events dispatched for default prevented wheel "
             "event, you need to initialize stateX and stateY");
  EventState stateX, stateY;
  if (scrollDeltaY) {
    SendLineScrollEvent(aTargetFrame, aEvent, stateY, scrollDeltaY,
                        DELTA_DIRECTION_Y);
    if (!targetFrame.IsAlive()) {
      *aStatus = nsEventStatus_eConsumeNoDefault;
      return;
    }
  }

  if (pixelDeltaY) {
    SendPixelScrollEvent(aTargetFrame, aEvent, stateY, pixelDeltaY,
                         DELTA_DIRECTION_Y);
    if (!targetFrame.IsAlive()) {
      *aStatus = nsEventStatus_eConsumeNoDefault;
      return;
    }
  }

  if (scrollDeltaX) {
    SendLineScrollEvent(aTargetFrame, aEvent, stateX, scrollDeltaX,
                        DELTA_DIRECTION_X);
    if (!targetFrame.IsAlive()) {
      *aStatus = nsEventStatus_eConsumeNoDefault;
      return;
    }
  }

  if (pixelDeltaX) {
    SendPixelScrollEvent(aTargetFrame, aEvent, stateX, pixelDeltaX,
                         DELTA_DIRECTION_X);
    if (!targetFrame.IsAlive()) {
      *aStatus = nsEventStatus_eConsumeNoDefault;
      return;
    }
  }

  if (stateY.mDefaultPrevented) {
    *aStatus = nsEventStatus_eConsumeNoDefault;
    aEvent->PreventDefault(!stateY.mDefaultPreventedByContent);
  }

  if (stateX.mDefaultPrevented) {
    *aStatus = nsEventStatus_eConsumeNoDefault;
    aEvent->PreventDefault(!stateX.mDefaultPreventedByContent);
  }
}

void EventStateManager::SendLineScrollEvent(nsIFrame* aTargetFrame,
                                            WidgetWheelEvent* aEvent,
                                            EventState& aState, int32_t aDelta,
                                            DeltaDirection aDeltaDirection) {
  nsCOMPtr<nsIContent> targetContent = aTargetFrame->GetContent();
  if (!targetContent) targetContent = GetFocusedContent();
  if (!targetContent) return;

  while (targetContent->IsText()) {
    targetContent = targetContent->GetFlattenedTreeParent();
  }

  WidgetMouseScrollEvent event(aEvent->IsTrusted(),
                               eLegacyMouseLineOrPageScroll, aEvent->mWidget);
  event.mFlags.mDefaultPrevented = aState.mDefaultPrevented;
  event.mFlags.mDefaultPreventedByContent = aState.mDefaultPreventedByContent;
  event.mRefPoint = aEvent->mRefPoint;
  event.mTime = aEvent->mTime;
  event.mTimeStamp = aEvent->mTimeStamp;
  event.mModifiers = aEvent->mModifiers;
  event.buttons = aEvent->buttons;
  event.mIsHorizontal = (aDeltaDirection == DELTA_DIRECTION_X);
  event.mDelta = aDelta;
  event.inputSource = aEvent->inputSource;

  nsEventStatus status = nsEventStatus_eIgnore;
  EventDispatcher::Dispatch(targetContent, aTargetFrame->PresContext(), &event,
                            nullptr, &status);
  aState.mDefaultPrevented =
      event.DefaultPrevented() || status == nsEventStatus_eConsumeNoDefault;
  aState.mDefaultPreventedByContent = event.DefaultPreventedByContent();
}

void EventStateManager::SendPixelScrollEvent(nsIFrame* aTargetFrame,
                                             WidgetWheelEvent* aEvent,
                                             EventState& aState,
                                             int32_t aPixelDelta,
                                             DeltaDirection aDeltaDirection) {
  nsCOMPtr<nsIContent> targetContent = aTargetFrame->GetContent();
  if (!targetContent) {
    targetContent = GetFocusedContent();
    if (!targetContent) return;
  }

  while (targetContent->IsText()) {
    targetContent = targetContent->GetFlattenedTreeParent();
  }

  WidgetMouseScrollEvent event(aEvent->IsTrusted(), eLegacyMousePixelScroll,
                               aEvent->mWidget);
  event.mFlags.mDefaultPrevented = aState.mDefaultPrevented;
  event.mFlags.mDefaultPreventedByContent = aState.mDefaultPreventedByContent;
  event.mRefPoint = aEvent->mRefPoint;
  event.mTime = aEvent->mTime;
  event.mTimeStamp = aEvent->mTimeStamp;
  event.mModifiers = aEvent->mModifiers;
  event.buttons = aEvent->buttons;
  event.mIsHorizontal = (aDeltaDirection == DELTA_DIRECTION_X);
  event.mDelta = aPixelDelta;
  event.inputSource = aEvent->inputSource;

  nsEventStatus status = nsEventStatus_eIgnore;
  EventDispatcher::Dispatch(targetContent, aTargetFrame->PresContext(), &event,
                            nullptr, &status);
  aState.mDefaultPrevented =
      event.DefaultPrevented() || status == nsEventStatus_eConsumeNoDefault;
  aState.mDefaultPreventedByContent = event.DefaultPreventedByContent();
}

nsIFrame* EventStateManager::ComputeScrollTargetAndMayAdjustWheelEvent(
    nsIFrame* aTargetFrame, WidgetWheelEvent* aEvent,
    ComputeScrollTargetOptions aOptions) {
  return ComputeScrollTargetAndMayAdjustWheelEvent(
      aTargetFrame, aEvent->mDeltaX, aEvent->mDeltaY, aEvent, aOptions);
}

// Overload ComputeScrollTargetAndMayAdjustWheelEvent method to allow passing
// "test" dx and dy when looking for which scrollbarmediators to activate when
// two finger down on trackpad and before any actual motion
nsIFrame* EventStateManager::ComputeScrollTargetAndMayAdjustWheelEvent(
    nsIFrame* aTargetFrame, double aDirectionX, double aDirectionY,
    WidgetWheelEvent* aEvent, ComputeScrollTargetOptions aOptions) {
  if ((aOptions & INCLUDE_PLUGIN_AS_TARGET) &&
      !WheelPrefs::WheelEventsEnabledOnPlugins()) {
    aOptions = RemovePluginFromTarget(aOptions);
  }

  bool isAutoDir = false;
  bool honoursRoot = false;
  if (MAY_BE_ADJUSTED_BY_AUTO_DIR & aOptions) {
    // If the scroll is respected as auto-dir, aDirection* should always be
    // equivalent to the event's delta vlaues(Currently, there are only one case
    // where aDirection*s have different values from the widget wheel event's
    // original delta values and the only case isn't auto-dir, see
    // ScrollbarsForWheel::TemporarilyActivateAllPossibleScrollTargets).
    MOZ_ASSERT(aDirectionX == aEvent->mDeltaX &&
               aDirectionY == aEvent->mDeltaY);

    WheelDeltaAdjustmentStrategy strategy =
        GetWheelDeltaAdjustmentStrategy(*aEvent);
    switch (strategy) {
      case WheelDeltaAdjustmentStrategy::eAutoDir:
        isAutoDir = true;
        honoursRoot = false;
        break;
      case WheelDeltaAdjustmentStrategy::eAutoDirWithRootHonour:
        isAutoDir = true;
        honoursRoot = true;
        break;
      default:
        break;
    }
  }

  if (aOptions & PREFER_MOUSE_WHEEL_TRANSACTION) {
    // If the user recently scrolled with the mousewheel, then they probably
    // want to scroll the same view as before instead of the view under the
    // cursor.  WheelTransaction tracks the frame currently being
    // scrolled with the mousewheel. We consider the transaction ended when the
    // mouse moves more than "mousewheel.transaction.ignoremovedelay"
    // milliseconds after the last scroll operation, or any time the mouse moves
    // out of the frame, or when more than "mousewheel.transaction.timeout"
    // milliseconds have passed after the last operation, even if the mouse
    // hasn't moved.
    nsIFrame* lastScrollFrame = WheelTransaction::GetTargetFrame();
    if (lastScrollFrame) {
      if (aOptions & INCLUDE_PLUGIN_AS_TARGET) {
        nsPluginFrame* pluginFrame = do_QueryFrame(lastScrollFrame);
        if (pluginFrame &&
            pluginFrame->WantsToHandleWheelEventAsDefaultAction()) {
          return lastScrollFrame;
        }
      }
      nsIScrollableFrame* scrollableFrame =
          lastScrollFrame->GetScrollTargetFrame();
      if (scrollableFrame) {
        nsIFrame* frameToScroll = do_QueryFrame(scrollableFrame);
        MOZ_ASSERT(frameToScroll);
        if (isAutoDir) {
          ESMAutoDirWheelDeltaAdjuster adjuster(*aEvent, *lastScrollFrame,
                                                honoursRoot);
          // Note that calling this function will not always cause the delta to
          // be adjusted, it only adjusts the delta when it should, because
          // Adjust() internally calls ShouldBeAdjusted() before making
          // adjustment.
          adjuster.Adjust();
        }
        return frameToScroll;
      }
    }
  }

  // If the event doesn't cause scroll actually, we cannot find scroll target
  // because we check if the event can cause scroll actually on each found
  // scrollable frame.
  if (!aDirectionX && !aDirectionY) {
    return nullptr;
  }

  bool checkIfScrollableX;
  bool checkIfScrollableY;
  if (isAutoDir) {
    // Always check the frame's scrollability in both the two directions for an
    // auto-dir scroll. That is, for an auto-dir scroll,
    // PREFER_ACTUAL_SCROLLABLE_TARGET_ALONG_X_AXIS and
    // PREFER_ACTUAL_SCROLLABLE_TARGET_ALONG_Y_AXIS should be ignored.
    checkIfScrollableX = true;
    checkIfScrollableY = true;
  } else {
    checkIfScrollableX =
        aDirectionX &&
        (aOptions & PREFER_ACTUAL_SCROLLABLE_TARGET_ALONG_X_AXIS);
    checkIfScrollableY =
        aDirectionY &&
        (aOptions & PREFER_ACTUAL_SCROLLABLE_TARGET_ALONG_Y_AXIS);
  }

  nsIFrame* scrollFrame = !(aOptions & START_FROM_PARENT)
                              ? aTargetFrame
                              : GetParentFrameToScroll(aTargetFrame);
  for (; scrollFrame; scrollFrame = GetParentFrameToScroll(scrollFrame)) {
    // Check whether the frame wants to provide us with a scrollable view.
    nsIScrollableFrame* scrollableFrame = scrollFrame->GetScrollTargetFrame();
    if (!scrollableFrame) {
      // If the frame is a plugin frame, then, the plugin content may handle
      // wheel events.  Only when the caller computes the scroll target for
      // default action handling, we should assume the plugin frame as
      // scrollable if the plugin wants to handle wheel events as default
      // action.
      if (aOptions & INCLUDE_PLUGIN_AS_TARGET) {
        nsPluginFrame* pluginFrame = do_QueryFrame(scrollFrame);
        if (pluginFrame &&
            pluginFrame->WantsToHandleWheelEventAsDefaultAction()) {
          return scrollFrame;
        }
      }
      nsMenuPopupFrame* menuPopupFrame = do_QueryFrame(scrollFrame);
      if (menuPopupFrame) {
        return nullptr;
      }
      continue;
    }

    nsIFrame* frameToScroll = do_QueryFrame(scrollableFrame);
    MOZ_ASSERT(frameToScroll);

    if (!checkIfScrollableX && !checkIfScrollableY) {
      return frameToScroll;
    }

    // If the frame disregards the direction the user is trying to scroll, then
    // it should just bubbles the scroll event up to its parental scroll frame
    Maybe<layers::ScrollDirection> disregardedDirection =
        WheelHandlingUtils::GetDisregardedWheelScrollDirection(scrollFrame);
    if (disregardedDirection) {
      switch (disregardedDirection.ref()) {
        case layers::ScrollDirection::eHorizontal:
          if (checkIfScrollableX) {
            continue;
          }
          break;
        case layers::ScrollDirection::eVertical:
          if (checkIfScrollableY) {
            continue;
          }
          break;
      }
    }

    ScrollStyles ss = scrollableFrame->GetScrollStyles();
    bool hiddenForV = (StyleOverflow::Hidden == ss.mVertical);
    bool hiddenForH = (StyleOverflow::Hidden == ss.mHorizontal);
    if ((hiddenForV && hiddenForH) ||
        (checkIfScrollableY && !checkIfScrollableX && hiddenForV) ||
        (checkIfScrollableX && !checkIfScrollableY && hiddenForH)) {
      continue;
    }

    // Computes whether the currently checked frame is scrollable by this wheel
    // event.
    bool canScroll = false;
    if (isAutoDir) {
      ESMAutoDirWheelDeltaAdjuster adjuster(*aEvent, *scrollFrame, honoursRoot);
      if (adjuster.ShouldBeAdjusted()) {
        adjuster.Adjust();
        canScroll = true;
      } else if (WheelHandlingUtils::CanScrollOn(scrollableFrame, aDirectionX,
                                                 aDirectionY)) {
        canScroll = true;
      }
    } else if (WheelHandlingUtils::CanScrollOn(scrollableFrame, aDirectionX,
                                               aDirectionY)) {
      canScroll = true;
    }

    // Comboboxes need special care.
    nsComboboxControlFrame* comboBox = do_QueryFrame(scrollFrame);
    if (comboBox) {
      if (comboBox->IsDroppedDown()) {
        // Don't propagate to parent when drop down menu is active.
        return canScroll ? frameToScroll : nullptr;
      }
      // Always propagate when not dropped down (even if focused).
      continue;
    }

    if (canScroll) {
      return frameToScroll;
    }

    // Where we are at is the block ending in a for loop.
    // The current frame has been checked to be unscrollable by this wheel
    // event, continue the loop to check its parent, if any.
  }

  nsIFrame* newFrame = nsLayoutUtils::GetCrossDocParentFrame(
      aTargetFrame->PresShell()->GetRootFrame());
  aOptions =
      static_cast<ComputeScrollTargetOptions>(aOptions & ~START_FROM_PARENT);
  if (!newFrame) {
    return nullptr;
  }
  return ComputeScrollTargetAndMayAdjustWheelEvent(newFrame, aEvent, aOptions);
}

nsSize EventStateManager::GetScrollAmount(
    nsPresContext* aPresContext, WidgetWheelEvent* aEvent,
    nsIScrollableFrame* aScrollableFrame) {
  MOZ_ASSERT(aPresContext);
  MOZ_ASSERT(aEvent);

  bool isPage = (aEvent->mDeltaMode == WheelEvent_Binding::DOM_DELTA_PAGE);
  if (aScrollableFrame) {
    return isPage ? aScrollableFrame->GetPageScrollAmount()
                  : aScrollableFrame->GetLineScrollAmount();
  }

  // If there is no scrollable frame and page scrolling, use viewport size.
  if (isPage) {
    return aPresContext->GetVisibleArea().Size();
  }

  // If there is no scrollable frame, we should use root frame's information.
  nsIFrame* rootFrame = aPresContext->PresShell()->GetRootFrame();
  if (!rootFrame) {
    return nsSize(0, 0);
  }
  RefPtr<nsFontMetrics> fm =
      nsLayoutUtils::GetInflatedFontMetricsForFrame(rootFrame);
  NS_ENSURE_TRUE(fm, nsSize(0, 0));
  return nsSize(fm->AveCharWidth(), fm->MaxHeight());
}

void EventStateManager::DoScrollText(nsIScrollableFrame* aScrollableFrame,
                                     WidgetWheelEvent* aEvent) {
  MOZ_ASSERT(aScrollableFrame);
  MOZ_ASSERT(aEvent);

  nsIFrame* scrollFrame = do_QueryFrame(aScrollableFrame);
  MOZ_ASSERT(scrollFrame);

  AutoWeakFrame scrollFrameWeak(scrollFrame);
  if (!WheelTransaction::WillHandleDefaultAction(aEvent, scrollFrameWeak)) {
    return;
  }

  // Default action's actual scroll amount should be computed from device
  // pixels.
  nsPresContext* pc = scrollFrame->PresContext();
  nsSize scrollAmount = GetScrollAmount(pc, aEvent, aScrollableFrame);
  nsIntSize scrollAmountInDevPixels(
      pc->AppUnitsToDevPixels(scrollAmount.width),
      pc->AppUnitsToDevPixels(scrollAmount.height));
  nsIntPoint actualDevPixelScrollAmount =
      DeltaAccumulator::GetInstance()->ComputeScrollAmountForDefaultAction(
          aEvent, scrollAmountInDevPixels);

  // Don't scroll around the axis whose overflow style is hidden.
  ScrollStyles overflowStyle = aScrollableFrame->GetScrollStyles();
  if (overflowStyle.mHorizontal == StyleOverflow::Hidden) {
    actualDevPixelScrollAmount.x = 0;
  }
  if (overflowStyle.mVertical == StyleOverflow::Hidden) {
    actualDevPixelScrollAmount.y = 0;
  }

  nsIScrollbarMediator::ScrollSnapMode snapMode =
      nsIScrollbarMediator::DISABLE_SNAP;
  nsAtom* origin = nullptr;
  switch (aEvent->mDeltaMode) {
    case WheelEvent_Binding::DOM_DELTA_LINE:
      origin = nsGkAtoms::mouseWheel;
      snapMode = nsIScrollableFrame::ENABLE_SNAP;
      break;
    case WheelEvent_Binding::DOM_DELTA_PAGE:
      origin = nsGkAtoms::pages;
      snapMode = nsIScrollableFrame::ENABLE_SNAP;
      break;
    case WheelEvent_Binding::DOM_DELTA_PIXEL:
      origin = nsGkAtoms::pixels;
      break;
    default:
      MOZ_CRASH("Invalid deltaMode value comes");
  }

  // We shouldn't scroll more one page at once except when over one page scroll
  // is allowed for the event.
  nsSize pageSize = aScrollableFrame->GetPageScrollAmount();
  nsIntSize devPixelPageSize(pc->AppUnitsToDevPixels(pageSize.width),
                             pc->AppUnitsToDevPixels(pageSize.height));
  if (!WheelPrefs::GetInstance()->IsOverOnePageScrollAllowedX(aEvent) &&
      DeprecatedAbs(actualDevPixelScrollAmount.x) > devPixelPageSize.width) {
    actualDevPixelScrollAmount.x = (actualDevPixelScrollAmount.x >= 0)
                                       ? devPixelPageSize.width
                                       : -devPixelPageSize.width;
  }

  if (!WheelPrefs::GetInstance()->IsOverOnePageScrollAllowedY(aEvent) &&
      DeprecatedAbs(actualDevPixelScrollAmount.y) > devPixelPageSize.height) {
    actualDevPixelScrollAmount.y = (actualDevPixelScrollAmount.y >= 0)
                                       ? devPixelPageSize.height
                                       : -devPixelPageSize.height;
  }

  bool isDeltaModePixel =
      (aEvent->mDeltaMode == WheelEvent_Binding::DOM_DELTA_PIXEL);

  nsIScrollableFrame::ScrollMode mode;
  switch (aEvent->mScrollType) {
    case WidgetWheelEvent::SCROLL_DEFAULT:
      if (isDeltaModePixel) {
        mode = nsIScrollableFrame::NORMAL;
      } else if (aEvent->mFlags.mHandledByAPZ) {
        mode = nsIScrollableFrame::SMOOTH_MSD;
      } else {
        mode = nsIScrollableFrame::SMOOTH;
      }
      break;
    case WidgetWheelEvent::SCROLL_SYNCHRONOUSLY:
      mode = nsIScrollableFrame::INSTANT;
      break;
    case WidgetWheelEvent::SCROLL_ASYNCHRONOUSELY:
      mode = nsIScrollableFrame::NORMAL;
      break;
    case WidgetWheelEvent::SCROLL_SMOOTHLY:
      mode = nsIScrollableFrame::SMOOTH;
      break;
    default:
      MOZ_CRASH("Invalid mScrollType value comes");
  }

  nsIScrollableFrame::ScrollMomentum momentum =
      aEvent->mIsMomentum ? nsIScrollableFrame::SYNTHESIZED_MOMENTUM_EVENT
                          : nsIScrollableFrame::NOT_MOMENTUM;

  nsIntPoint overflow;
  aScrollableFrame->ScrollBy(actualDevPixelScrollAmount,
                             nsIScrollableFrame::DEVICE_PIXELS, mode, &overflow,
                             origin, momentum, snapMode);

  if (!scrollFrameWeak.IsAlive()) {
    // If the scroll causes changing the layout, we can think that the event
    // has been completely consumed by the content.  Then, users probably don't
    // want additional action.
    aEvent->mOverflowDeltaX = aEvent->mOverflowDeltaY = 0;
  } else if (isDeltaModePixel) {
    aEvent->mOverflowDeltaX = overflow.x;
    aEvent->mOverflowDeltaY = overflow.y;
  } else {
    aEvent->mOverflowDeltaX =
        static_cast<double>(overflow.x) / scrollAmountInDevPixels.width;
    aEvent->mOverflowDeltaY =
        static_cast<double>(overflow.y) / scrollAmountInDevPixels.height;
  }

  // If CSS overflow properties caused not to scroll, the overflowDelta* values
  // should be same as delta* values since they may be used as gesture event by
  // widget.  However, if there is another scrollable element in the ancestor
  // along the axis, probably users don't want the operation to cause
  // additional action such as moving history.  In such case, overflowDelta
  // values should stay zero.
  if (scrollFrameWeak.IsAlive()) {
    if (aEvent->mDeltaX && overflowStyle.mHorizontal == StyleOverflow::Hidden &&
        !ComputeScrollTargetAndMayAdjustWheelEvent(
            scrollFrame, aEvent,
            COMPUTE_SCROLLABLE_ANCESTOR_ALONG_X_AXIS_WITH_AUTO_DIR)) {
      aEvent->mOverflowDeltaX = aEvent->mDeltaX;
    }
    if (aEvent->mDeltaY && overflowStyle.mVertical == StyleOverflow::Hidden &&
        !ComputeScrollTargetAndMayAdjustWheelEvent(
            scrollFrame, aEvent,
            COMPUTE_SCROLLABLE_ANCESTOR_ALONG_Y_AXIS_WITH_AUTO_DIR)) {
      aEvent->mOverflowDeltaY = aEvent->mDeltaY;
    }
  }

  NS_ASSERTION(
      aEvent->mOverflowDeltaX == 0 ||
          (aEvent->mOverflowDeltaX > 0) == (aEvent->mDeltaX > 0),
      "The sign of mOverflowDeltaX is different from the scroll direction");
  NS_ASSERTION(
      aEvent->mOverflowDeltaY == 0 ||
          (aEvent->mOverflowDeltaY > 0) == (aEvent->mDeltaY > 0),
      "The sign of mOverflowDeltaY is different from the scroll direction");

  WheelPrefs::GetInstance()->CancelApplyingUserPrefsFromOverflowDelta(aEvent);
}

void EventStateManager::DecideGestureEvent(WidgetGestureNotifyEvent* aEvent,
                                           nsIFrame* targetFrame) {
  NS_ASSERTION(aEvent->mMessage == eGestureNotify,
               "DecideGestureEvent called with a non-gesture event");

  /* Check the ancestor tree to decide if any frame is willing* to receive
   * a MozPixelScroll event. If that's the case, the current touch gesture
   * will be used as a pan gesture; otherwise it will be a regular
   * mousedown/mousemove/click event.
   *
   * *willing: determine if it makes sense to pan the element using scroll
   * events:
   *  - For web content: if there are any visible scrollbars on the touch point
   *  - For XUL: if it's an scrollable element that can currently scroll in some
   *    direction.
   *
   * Note: we'll have to one-off various cases to ensure a good usable behavior
   */
  WidgetGestureNotifyEvent::PanDirection panDirection =
      WidgetGestureNotifyEvent::ePanNone;
  bool displayPanFeedback = false;
  for (nsIFrame* current = targetFrame; current;
       current = nsLayoutUtils::GetCrossDocParentFrame(current)) {
    // e10s - mark remote content as pannable. This is a work around since
    // we don't have access to remote frame scroll info here. Apz data may
    // assist is solving this.
    if (current && IsRemoteTarget(current->GetContent())) {
      panDirection = WidgetGestureNotifyEvent::ePanBoth;
      // We don't know when we reach bounds, so just disable feedback for now.
      displayPanFeedback = false;
      break;
    }

    LayoutFrameType currentFrameType = current->Type();

    // Scrollbars should always be draggable
    if (currentFrameType == LayoutFrameType::Scrollbar) {
      panDirection = WidgetGestureNotifyEvent::ePanNone;
      break;
    }

#ifdef MOZ_XUL
    // Special check for trees
    nsTreeBodyFrame* treeFrame = do_QueryFrame(current);
    if (treeFrame) {
      if (treeFrame->GetHorizontalOverflow()) {
        panDirection = WidgetGestureNotifyEvent::ePanHorizontal;
      }
      if (treeFrame->GetVerticalOverflow()) {
        panDirection = WidgetGestureNotifyEvent::ePanVertical;
      }
      break;
    }
#endif

    nsIScrollableFrame* scrollableFrame = do_QueryFrame(current);
    if (scrollableFrame) {
      if (current->IsFrameOfType(nsIFrame::eXULBox)) {
        displayPanFeedback = true;

        nsRect scrollRange = scrollableFrame->GetScrollRange();
        bool canScrollHorizontally = scrollRange.width > 0;

        if (targetFrame->IsMenuFrame()) {
          // menu frames report horizontal scroll when they have submenus
          // and we don't want that
          canScrollHorizontally = false;
          displayPanFeedback = false;
        }

        // Vertical panning has priority over horizontal panning, so
        // when vertical movement is possible we can just finish the loop.
        if (scrollRange.height > 0) {
          panDirection = WidgetGestureNotifyEvent::ePanVertical;
          break;
        }

        if (canScrollHorizontally) {
          panDirection = WidgetGestureNotifyEvent::ePanHorizontal;
          displayPanFeedback = false;
        }
      } else {  // Not a XUL box
        uint32_t scrollbarVisibility =
            scrollableFrame->GetScrollbarVisibility();

        // Check if we have visible scrollbars
        if (scrollbarVisibility & nsIScrollableFrame::VERTICAL) {
          panDirection = WidgetGestureNotifyEvent::ePanVertical;
          displayPanFeedback = true;
          break;
        }

        if (scrollbarVisibility & nsIScrollableFrame::HORIZONTAL) {
          panDirection = WidgetGestureNotifyEvent::ePanHorizontal;
          displayPanFeedback = true;
        }
      }
    }  // scrollableFrame
  }    // ancestor chain
  aEvent->mDisplayPanFeedback = displayPanFeedback;
  aEvent->mPanDirection = panDirection;
}

#ifdef XP_MACOSX
static bool NodeAllowsClickThrough(nsINode* aNode) {
  while (aNode) {
    if (aNode->IsXULElement(nsGkAtoms::browser)) {
      return false;
    }
    if (aNode->IsXULElement()) {
      mozilla::dom::Element* element = aNode->AsElement();
      static Element::AttrValuesArray strings[] = {nsGkAtoms::always,
                                                   nsGkAtoms::never, nullptr};
      switch (element->FindAttrValueIn(
          kNameSpaceID_None, nsGkAtoms::clickthrough, strings, eCaseMatters)) {
        case 0:
          return true;
        case 1:
          return false;
      }
    }
    aNode = nsContentUtils::GetCrossDocParentNode(aNode);
  }
  return true;
}
#endif

void EventStateManager::PostHandleKeyboardEvent(
    WidgetKeyboardEvent* aKeyboardEvent, nsIFrame* aTargetFrame,
    nsEventStatus& aStatus) {
  if (aStatus == nsEventStatus_eConsumeNoDefault) {
    return;
  }

  if (!aKeyboardEvent->HasBeenPostedToRemoteProcess()) {
    if (aKeyboardEvent->IsWaitingReplyFromRemoteProcess()) {
      RefPtr<TabParent> remote =
          aTargetFrame ? TabParent::GetFrom(aTargetFrame->GetContent())
                       : nullptr;
      if (remote && aKeyboardEvent->mLayersId.IsValid()) {
        // remote is null-checked above in order to let pre-existing event
        // targeting code's chrome vs. content decision override APZ if they
        // disagree in order not to disrupt non-Fission e10s mode in case
        // there are still bugs in the Fission-mode code. That is, if remote
        // is nullptr, the pre-existing event targeting code has deemed this
        // event to belong to chrome rather than content.
        TabParent* preciseRemote =
            TabParent::GetTabParentFromLayersId(aKeyboardEvent->mLayersId);
        if (preciseRemote) {
          remote = preciseRemote;
        }
        // else there was a race between APZ and the chrome-process LayersId
        // to TabParent mapping.
      }
      if (remote && !remote->IsReadyToHandleInputEvents()) {
        // We need to dispatch the event to the browser element again if we were
        // waiting for the key reply but the event wasn't sent to the content
        // process due to the remote browser wasn't ready.
        WidgetKeyboardEvent keyEvent(*aKeyboardEvent);
        aKeyboardEvent->MarkAsHandledInRemoteProcess();
        EventDispatcher::Dispatch(remote->GetOwnerElement(), mPresContext,
                                  &keyEvent);
        if (keyEvent.DefaultPrevented()) {
          aKeyboardEvent->PreventDefault(!keyEvent.DefaultPreventedByContent());
          aStatus = nsEventStatus_eConsumeNoDefault;
          return;
        }
      }
    }
    // The widget expects a reply for every keyboard event. If the event wasn't
    // dispatched to a content process (non-e10s or no content process
    // running), we need to short-circuit here. Otherwise, we need to wait for
    // the content process to handle the event.
    if (aKeyboardEvent->mWidget) {
      aKeyboardEvent->mWidget->PostHandleKeyEvent(aKeyboardEvent);
    }
    if (aKeyboardEvent->DefaultPrevented()) {
      aStatus = nsEventStatus_eConsumeNoDefault;
      return;
    }
  }

  // XXX Currently, our automated tests don't support mKeyNameIndex.
  //     Therefore, we still need to handle this with keyCode.
  switch (aKeyboardEvent->mKeyCode) {
    case NS_VK_TAB:
    case NS_VK_F6:
      // This is to prevent keyboard scrolling while alt modifier in use.
      if (!aKeyboardEvent->IsAlt()) {
        aStatus = nsEventStatus_eConsumeNoDefault;

        // Handling the tab event after it was sent to content is bad,
        // because to the FocusManager the remote-browser looks like one
        // element, so we would just move the focus to the next element
        // in chrome, instead of handling it in content.
        if (aKeyboardEvent->HasBeenPostedToRemoteProcess()) {
          break;
        }

        EnsureDocument(mPresContext);
        nsIFocusManager* fm = nsFocusManager::GetFocusManager();
        if (fm && mDocument) {
          // Shift focus forward or back depending on shift key
          bool isDocMove = aKeyboardEvent->IsControl() ||
                           aKeyboardEvent->mKeyCode == NS_VK_F6;
          uint32_t dir =
              aKeyboardEvent->IsShift()
                  ? (isDocMove ? static_cast<uint32_t>(
                                     nsIFocusManager::MOVEFOCUS_BACKWARDDOC)
                               : static_cast<uint32_t>(
                                     nsIFocusManager::MOVEFOCUS_BACKWARD))
                  : (isDocMove ? static_cast<uint32_t>(
                                     nsIFocusManager::MOVEFOCUS_FORWARDDOC)
                               : static_cast<uint32_t>(
                                     nsIFocusManager::MOVEFOCUS_FORWARD));
          RefPtr<Element> result;
          fm->MoveFocus(mDocument->GetWindow(), nullptr, dir,
                        nsIFocusManager::FLAG_BYKEY, getter_AddRefs(result));
        }
      }
      return;
    case 0:
      // We handle keys with no specific keycode value below.
      break;
    default:
      return;
  }

  switch (aKeyboardEvent->mKeyNameIndex) {
    case KEY_NAME_INDEX_ZoomIn:
    case KEY_NAME_INDEX_ZoomOut:
      ChangeFullZoom(
          aKeyboardEvent->mKeyNameIndex == KEY_NAME_INDEX_ZoomIn ? 1 : -1);
      aStatus = nsEventStatus_eConsumeNoDefault;
      break;
    default:
      break;
  }
}

nsresult EventStateManager::PostHandleEvent(nsPresContext* aPresContext,
                                            WidgetEvent* aEvent,
                                            nsIFrame* aTargetFrame,
                                            nsEventStatus* aStatus,
                                            nsIContent* aOverrideClickTarget) {
  NS_ENSURE_ARG(aPresContext);
  NS_ENSURE_ARG_POINTER(aStatus);

  mCurrentTarget = aTargetFrame;
  mCurrentTargetContent = nullptr;

  HandleCrossProcessEvent(aEvent, aStatus);
  // NOTE: the above call may have destroyed aTargetFrame, please use
  // mCurrentTarget henceforth.  This is to avoid using it accidentally:
  aTargetFrame = nullptr;

  // Most of the events we handle below require a frame.
  // Add special cases here.
  if (!mCurrentTarget && aEvent->mMessage != eMouseUp &&
      aEvent->mMessage != eMouseDown && aEvent->mMessage != eDragEnter &&
      aEvent->mMessage != eDragOver) {
    return NS_OK;
  }

  // Keep the prescontext alive, we might need it after event dispatch
  RefPtr<nsPresContext> presContext = aPresContext;
  nsresult ret = NS_OK;

  switch (aEvent->mMessage) {
    case eMouseDown: {
      WidgetMouseEvent* mouseEvent = aEvent->AsMouseEvent();
      if (mouseEvent->button == WidgetMouseEvent::eLeftButton &&
          !sNormalLMouseEventInProcess) {
        // We got a mouseup event while a mousedown event was being processed.
        // Make sure that the capturing content is cleared.
        nsIPresShell::SetCapturingContent(nullptr, 0);
        break;
      }

      // For remote content, capture the event in the parent process at the
      // <xul:browser remote> element. This will ensure that subsequent
      // mousemove/mouseup events will continue to be dispatched to this element
      // and therefore forwarded to the child.
      if (aEvent->HasBeenPostedToRemoteProcess() &&
          !nsIPresShell::GetCapturingContent()) {
        nsIContent* content =
            mCurrentTarget ? mCurrentTarget->GetContent() : nullptr;
        nsIPresShell::SetCapturingContent(content, 0);
      }

      nsCOMPtr<nsIContent> activeContent;
      // When content calls PreventDefault on pointerdown, we also call
      // PreventDefault on the subsequent mouse events to suppress default
      // behaviors. Normally, aStatus should be nsEventStatus_eConsumeNoDefault
      // when the event is DefaultPrevented but it's reset to
      // nsEventStatus_eIgnore in EventStateManager::PreHandleEvent. So we also
      // check if the event is DefaultPrevented.
      if (nsEventStatus_eConsumeNoDefault != *aStatus &&
          !aEvent->DefaultPrevented()) {
        nsCOMPtr<nsIContent> newFocus;
        bool suppressBlur = false;
        if (mCurrentTarget) {
          mCurrentTarget->GetContentForEvent(aEvent, getter_AddRefs(newFocus));
          const nsStyleUI* ui = mCurrentTarget->StyleUI();
          activeContent = mCurrentTarget->GetContent();

          // In some cases, we do not want to even blur the current focused
          // element. Those cases are:
          // 1. -moz-user-focus CSS property is set to 'ignore';
          // 2. Element with NS_EVENT_STATE_DISABLED
          //    (aka :disabled pseudo-class for HTML element);
          // 3. XUL control element has the disabled property set to 'true'.
          //
          // We can't use nsIFrame::IsFocusable() because we want to blur when
          // we click on a visibility: none element.
          // We can't use nsIContent::IsFocusable() because we want to blur when
          // we click on a non-focusable element like a <div>.
          // We have to use |aEvent->mTarget| to not make sure we do not check
          // an anonymous node of the targeted element.
          suppressBlur = (ui->mUserFocus == StyleUserFocus::Ignore);

          nsCOMPtr<Element> element = do_QueryInterface(aEvent->mTarget);
          if (!suppressBlur) {
            suppressBlur =
                element && element->State().HasState(NS_EVENT_STATE_DISABLED);
          }

          if (!suppressBlur && element) {
            nsCOMPtr<nsIDOMXULControlElement> xulControl =
                element->AsXULControl();
            if (xulControl) {
              bool disabled;
              xulControl->GetDisabled(&disabled);
              suppressBlur = disabled;
            }
          }
        }

        if (!suppressBlur) {
          suppressBlur = nsContentUtils::IsUserFocusIgnored(activeContent);
        }

        // When a root content which isn't editable but has an editable HTML
        // <body> element is clicked, we should redirect the focus to the
        // the <body> element.  E.g., when an user click bottom of the editor
        // where is outside of the <body> element, the <body> should be focused
        // and the user can edit immediately after that.
        //
        // NOTE: The newFocus isn't editable that also means it's not in
        // designMode.  In designMode, all contents are not focusable.
        if (newFocus && !newFocus->IsEditable()) {
          Document* doc = newFocus->GetComposedDoc();
          if (doc && newFocus == doc->GetRootElement()) {
            nsIContent* bodyContent =
                nsLayoutUtils::GetEditableRootContentByContentEditable(doc);
            if (bodyContent && bodyContent->GetPrimaryFrame()) {
              newFocus = bodyContent;
            }
          }
        }

        // When the mouse is pressed, the default action is to focus the
        // target. Look for the nearest enclosing focusable frame.
        //
        // TODO: Probably this should be moved to Element::PostHandleEvent.
        for (; newFocus; newFocus = newFocus->GetFlattenedTreeParent()) {
          if (!newFocus->IsElement()) {
            continue;
          }

          nsIFrame* frame = newFocus->GetPrimaryFrame();
          if (!frame) {
            continue;
          }

          // If the mousedown happened inside a popup, don't try to set focus on
          // one of its containing elements
          if (frame->StyleDisplay()->mDisplay == StyleDisplay::MozPopup) {
            newFocus = nullptr;
            break;
          }

          int32_t tabIndexUnused;
          if (frame->IsFocusable(&tabIndexUnused, true)) {
            break;
          }
        }

        MOZ_ASSERT_IF(newFocus, newFocus->IsElement());

        nsIFocusManager* fm = nsFocusManager::GetFocusManager();
        if (fm) {
          // if something was found to focus, focus it. Otherwise, if the
          // element that was clicked doesn't have -moz-user-focus: ignore,
          // clear the existing focus. For -moz-user-focus: ignore, the focus
          // is just left as is.
          // Another effect of mouse clicking, handled in nsSelection, is that
          // it should update the caret position to where the mouse was
          // clicked. Because the focus is cleared when clicking on a
          // non-focusable node, the next press of the tab key will cause
          // focus to be shifted from the caret position instead of the root.
          if (newFocus) {
            // use the mouse flag and the noscroll flag so that the content
            // doesn't unexpectedly scroll when clicking an element that is
            // only half visible
            uint32_t flags =
                nsIFocusManager::FLAG_BYMOUSE | nsIFocusManager::FLAG_NOSCROLL;
            // If this was a touch-generated event, pass that information:
            if (mouseEvent->inputSource ==
                MouseEvent_Binding::MOZ_SOURCE_TOUCH) {
              flags |= nsIFocusManager::FLAG_BYTOUCH;
            }
            fm->SetFocus(newFocus->AsElement(), flags);
          } else if (!suppressBlur) {
            // clear the focus within the frame and then set it as the
            // focused frame
            EnsureDocument(mPresContext);
            if (mDocument) {
#ifdef XP_MACOSX
              if (!activeContent || !activeContent->IsXULElement())
#endif
                fm->ClearFocus(mDocument->GetWindow());
              fm->SetFocusedWindow(mDocument->GetWindow());
            }
          }
        }

        // The rest is left button-specific.
        if (mouseEvent->button != WidgetMouseEvent::eLeftButton) {
          break;
        }

        // The nearest enclosing element goes into the :active state.  If we're
        // not an element (so we're text or something) we need to obtain
        // our parent element and put it into :active instead.
        if (activeContent && !activeContent->IsElement()) {
          if (nsIContent* par = activeContent->GetFlattenedTreeParent()) {
            activeContent = par;
          }
        }
      } else {
        // if we're here, the event handler returned false, so stop
        // any of our own processing of a drag. Workaround for bug 43258.
        StopTrackingDragGesture();

        // When the event was cancelled, there is currently a chrome document
        // focused and a mousedown just occurred on a content document, ensure
        // that the window that was clicked is focused.
        EnsureDocument(mPresContext);
        nsIFocusManager* fm = nsFocusManager::GetFocusManager();
        if (mDocument && fm) {
          nsCOMPtr<mozIDOMWindowProxy> window;
          fm->GetFocusedWindow(getter_AddRefs(window));
          auto* currentWindow = nsPIDOMWindowOuter::From(window);
          if (currentWindow && mDocument->GetWindow() &&
              currentWindow != mDocument->GetWindow() &&
              !nsContentUtils::IsChromeDoc(mDocument)) {
            nsCOMPtr<nsPIDOMWindowOuter> currentTop;
            nsCOMPtr<nsPIDOMWindowOuter> newTop;
            currentTop = currentWindow->GetTop();
            newTop = mDocument->GetWindow()->GetTop();
            nsCOMPtr<Document> currentDoc = currentWindow->GetExtantDoc();
            if (nsContentUtils::IsChromeDoc(currentDoc) ||
                (currentTop && newTop && currentTop != newTop)) {
              fm->SetFocusedWindow(mDocument->GetWindow());
            }
          }
        }
      }
      SetActiveManager(this, activeContent);
    } break;
    case ePointerCancel:
    case ePointerUp: {
      WidgetPointerEvent* pointerEvent = aEvent->AsPointerEvent();
      MOZ_ASSERT(pointerEvent);
      // Implicitly releasing capture for given pointer. ePointerLostCapture
      // should be send after ePointerUp or ePointerCancel.
      PointerEventHandler::ImplicitlyReleasePointerCapture(pointerEvent);

      if (pointerEvent->mMessage == ePointerCancel ||
          pointerEvent->inputSource == MouseEvent_Binding::MOZ_SOURCE_TOUCH) {
        // After pointercancel, pointer becomes invalid so we can remove
        // relevant helper from table. Regarding pointerup with non-hoverable
        // device, the pointer also becomes invalid. Hoverable (mouse/pen)
        // pointers are valid all the time (not only between down/up).
        GenerateMouseEnterExit(pointerEvent);
        mPointersEnterLeaveHelper.Remove(pointerEvent->pointerId);
      }
      break;
    }
    case eMouseUp: {
      ClearGlobalActiveContent(this);
      WidgetMouseEvent* mouseUpEvent = aEvent->AsMouseEvent();
      if (mouseUpEvent && EventCausesClickEvents(*mouseUpEvent)) {
        // Make sure to dispatch the click even if there is no frame for
        // the current target element. This is required for Web compatibility.
        RefPtr<EventStateManager> esm =
            ESMFromContentOrThis(aOverrideClickTarget);
        ret =
            esm->PostHandleMouseUp(mouseUpEvent, aStatus, aOverrideClickTarget);
      }

      nsIPresShell* shell = presContext->GetPresShell();
      if (shell) {
        RefPtr<nsFrameSelection> frameSelection = shell->FrameSelection();
        frameSelection->SetDragState(false);
      }
    } break;
    case eWheelOperationEnd: {
      MOZ_ASSERT(aEvent->IsTrusted());
      ScrollbarsForWheel::MayInactivate();
      WidgetWheelEvent* wheelEvent = aEvent->AsWheelEvent();
      nsIScrollableFrame* scrollTarget =
          do_QueryFrame(ComputeScrollTargetAndMayAdjustWheelEvent(
              mCurrentTarget, wheelEvent,
              COMPUTE_DEFAULT_ACTION_TARGET_WITH_AUTO_DIR));
      if (scrollTarget) {
        scrollTarget->ScrollSnap();
      }
    } break;
    case eWheel:
    case eWheelOperationStart: {
      MOZ_ASSERT(aEvent->IsTrusted());

      if (*aStatus == nsEventStatus_eConsumeNoDefault) {
        ScrollbarsForWheel::Inactivate();
        break;
      }

      WidgetWheelEvent* wheelEvent = aEvent->AsWheelEvent();
      MOZ_ASSERT(wheelEvent);

      // When APZ is enabled, the actual scroll animation might be handled by
      // the compositor.
      WheelPrefs::Action action =
          wheelEvent->mFlags.mHandledByAPZ
              ? WheelPrefs::ACTION_NONE
              : WheelPrefs::GetInstance()->ComputeActionFor(wheelEvent);

      WheelDeltaAdjustmentStrategy strategy =
          GetWheelDeltaAdjustmentStrategy(*wheelEvent);
      // Adjust the delta values of the wheel event if the current default
      // action is to horizontalize scrolling. I.e., deltaY values are set to
      // deltaX and deltaY and deltaZ values are set to 0.
      // If horizontalized, the delta values will be restored and its overflow
      // deltaX will become 0 when the WheelDeltaHorizontalizer instance is
      // being destroyed.
      WheelDeltaHorizontalizer horizontalizer(*wheelEvent);
      if (WheelDeltaAdjustmentStrategy::eHorizontalize == strategy) {
        horizontalizer.Horizontalize();
      }

      // Since ComputeScrollTargetAndMayAdjustWheelEvent() may adjust the delta
      // if the event is auto-dir. So we use |ESMAutoDirWheelDeltaRestorer|
      // here.
      // An instance of |ESMAutoDirWheelDeltaRestorer| is used to monitor
      // auto-dir adjustment which may happen during its lifetime. If the delta
      // values is adjusted during its lifetime, the instance will restore the
      // adjusted delta when it's being destrcuted.
      ESMAutoDirWheelDeltaRestorer restorer(*wheelEvent);
      // Check if the frame to scroll before checking the default action
      // because if the scroll target is a plugin, the default action should be
      // chosen by the plugin rather than by our prefs.
      nsIFrame* frameToScroll = ComputeScrollTargetAndMayAdjustWheelEvent(
          mCurrentTarget, wheelEvent,
          COMPUTE_DEFAULT_ACTION_TARGET_WITH_AUTO_DIR);
      nsPluginFrame* pluginFrame = do_QueryFrame(frameToScroll);
      if (pluginFrame) {
        MOZ_ASSERT(pluginFrame->WantsToHandleWheelEventAsDefaultAction());
        // Plugins should receive original values instead of adjusted values.
        horizontalizer.CancelHorizontalization();
        action = WheelPrefs::ACTION_SEND_TO_PLUGIN;
      }

      switch (action) {
        case WheelPrefs::ACTION_SCROLL:
        case WheelPrefs::ACTION_HORIZONTALIZED_SCROLL: {
          // For scrolling of default action, we should honor the mouse wheel
          // transaction.

          ScrollbarsForWheel::PrepareToScrollText(this, mCurrentTarget,
                                                  wheelEvent);

          if (aEvent->mMessage != eWheel ||
              (!wheelEvent->mDeltaX && !wheelEvent->mDeltaY)) {
            break;
          }

          nsIScrollableFrame* scrollTarget = do_QueryFrame(frameToScroll);
          ScrollbarsForWheel::SetActiveScrollTarget(scrollTarget);

          nsIFrame* rootScrollFrame =
              !mCurrentTarget
                  ? nullptr
                  : mCurrentTarget->PresShell()->GetRootScrollFrame();
          nsIScrollableFrame* rootScrollableFrame = nullptr;
          if (rootScrollFrame) {
            rootScrollableFrame = do_QueryFrame(rootScrollFrame);
          }
          if (!scrollTarget || scrollTarget == rootScrollableFrame) {
            wheelEvent->mViewPortIsOverscrolled = true;
          }
          wheelEvent->mOverflowDeltaX = wheelEvent->mDeltaX;
          wheelEvent->mOverflowDeltaY = wheelEvent->mDeltaY;
          WheelPrefs::GetInstance()->CancelApplyingUserPrefsFromOverflowDelta(
              wheelEvent);
          if (scrollTarget) {
            DoScrollText(scrollTarget, wheelEvent);
          } else {
            WheelTransaction::EndTransaction();
            ScrollbarsForWheel::Inactivate();
          }
          break;
        }
        case WheelPrefs::ACTION_HISTORY: {
          // If this event doesn't cause eLegacyMouseLineOrPageScroll event or
          // the direction is oblique, don't perform history back/forward.
          int32_t intDelta = wheelEvent->GetPreferredIntDelta();
          if (!intDelta) {
            break;
          }
          DoScrollHistory(intDelta);
          break;
        }
        case WheelPrefs::ACTION_ZOOM: {
          // If this event doesn't cause eLegacyMouseLineOrPageScroll event or
          // the direction is oblique, don't perform zoom in/out.
          int32_t intDelta = wheelEvent->GetPreferredIntDelta();
          if (!intDelta) {
            break;
          }
          DoScrollZoom(mCurrentTarget, intDelta);
          break;
        }
        case WheelPrefs::ACTION_SEND_TO_PLUGIN:
          MOZ_ASSERT(pluginFrame);

          if (wheelEvent->mMessage != eWheel ||
              (!wheelEvent->mDeltaX && !wheelEvent->mDeltaY)) {
            break;
          }

          MOZ_ASSERT(static_cast<void*>(frameToScroll) ==
                     static_cast<void*>(pluginFrame));
          if (!WheelTransaction::WillHandleDefaultAction(wheelEvent,
                                                         frameToScroll)) {
            break;
          }

          pluginFrame->HandleWheelEventAsDefaultAction(wheelEvent);
          break;
        case WheelPrefs::ACTION_NONE:
        default:
          bool allDeltaOverflown = false;
          if (wheelEvent->mFlags.mHandledByAPZ) {
            if (wheelEvent->mCanTriggerSwipe) {
              // For events that can trigger swipes, APZ needs to know whether
              // scrolling is possible in the requested direction. It does this
              // by looking at the scroll overflow values on mCanTriggerSwipe
              // events after they have been processed.
              allDeltaOverflown = !ComputeScrollTarget(
                  mCurrentTarget, wheelEvent, COMPUTE_DEFAULT_ACTION_TARGET);
            }
          } else {
            // The event was processed neither by APZ nor by us, so all of the
            // delta values must be overflown delta values.
            allDeltaOverflown = true;
          }

          if (!allDeltaOverflown) {
            break;
          }
          wheelEvent->mOverflowDeltaX = wheelEvent->mDeltaX;
          wheelEvent->mOverflowDeltaY = wheelEvent->mDeltaY;
          WheelPrefs::GetInstance()->CancelApplyingUserPrefsFromOverflowDelta(
              wheelEvent);
          wheelEvent->mViewPortIsOverscrolled = true;
          break;
      }
      *aStatus = nsEventStatus_eConsumeNoDefault;
    } break;

    case eGestureNotify: {
      if (nsEventStatus_eConsumeNoDefault != *aStatus) {
        DecideGestureEvent(aEvent->AsGestureNotifyEvent(), mCurrentTarget);
      }
    } break;

    case eDragEnter:
    case eDragOver: {
      NS_ASSERTION(aEvent->mClass == eDragEventClass, "Expected a drag event");

      // Check if the drag is occurring inside a scrollable area. If so, scroll
      // the area when the mouse is near the edges.
      if (mCurrentTarget && aEvent->mMessage == eDragOver) {
        nsIFrame* checkFrame = mCurrentTarget;
        while (checkFrame) {
          nsIScrollableFrame* scrollFrame = do_QueryFrame(checkFrame);
          // Break out so only the innermost scrollframe is scrolled.
          if (scrollFrame && scrollFrame->DragScroll(aEvent)) {
            break;
          }
          checkFrame = checkFrame->GetParent();
        }
      }

      nsCOMPtr<nsIDragSession> dragSession = nsContentUtils::GetDragSession();
      if (!dragSession) break;

      // Reset the flag.
      dragSession->SetOnlyChromeDrop(false);
      if (mPresContext) {
        EnsureDocument(mPresContext);
      }
      bool isChromeDoc = nsContentUtils::IsChromeDoc(mDocument);

      // the initial dataTransfer is the one from the dragstart event that
      // was set on the dragSession when the drag began.
      RefPtr<DataTransfer> dataTransfer;
      RefPtr<DataTransfer> initialDataTransfer = dragSession->GetDataTransfer();

      WidgetDragEvent* dragEvent = aEvent->AsDragEvent();

      // collect any changes to moz cursor settings stored in the event's
      // data transfer.
      UpdateDragDataTransfer(dragEvent);

      // cancelling a dragenter or dragover event means that a drop should be
      // allowed, so update the dropEffect and the canDrop state to indicate
      // that a drag is allowed. If the event isn't cancelled, a drop won't be
      // allowed. Essentially, to allow a drop somewhere, specify the effects
      // using the effectAllowed and dropEffect properties in a dragenter or
      // dragover event and cancel the event. To not allow a drop somewhere,
      // don't cancel the event or set the effectAllowed or dropEffect to
      // "none". This way, if the event is just ignored, no drop will be
      // allowed.
      uint32_t dropEffect = nsIDragService::DRAGDROP_ACTION_NONE;
      uint32_t action = nsIDragService::DRAGDROP_ACTION_NONE;
      if (nsEventStatus_eConsumeNoDefault == *aStatus) {
        // if the event has a dataTransfer set, use it.
        if (dragEvent->mDataTransfer) {
          // get the dataTransfer and the dropEffect that was set on it
          dataTransfer = dragEvent->mDataTransfer;
          dropEffect = dataTransfer->DropEffectInt();
        } else {
          // if dragEvent->mDataTransfer is null, it means that no attempt was
          // made to access the dataTransfer during the event, yet the event
          // was cancelled. Instead, use the initial data transfer available
          // from the drag session. The drop effect would not have been
          // initialized (which is done in DragEvent::GetDataTransfer),
          // so set it from the drag action. We'll still want to filter it
          // based on the effectAllowed below.
          dataTransfer = initialDataTransfer;

          dragSession->GetDragAction(&action);

          // filter the drop effect based on the action. Use UNINITIALIZED as
          // any effect is allowed.
          dropEffect = nsContentUtils::FilterDropEffect(
              action, nsIDragService::DRAGDROP_ACTION_UNINITIALIZED);
        }

        // At this point, if the dataTransfer is null, it means that the
        // drag was originally started by directly calling the drag service.
        // Just assume that all effects are allowed.
        uint32_t effectAllowed = nsIDragService::DRAGDROP_ACTION_UNINITIALIZED;
        if (dataTransfer) {
          effectAllowed = dataTransfer->EffectAllowedInt();
        }

        // set the drag action based on the drop effect and effect allowed.
        // The drop effect field on the drag transfer object specifies the
        // desired current drop effect. However, it cannot be used if the
        // effectAllowed state doesn't include that type of action. If the
        // dropEffect is "none", then the action will be 'none' so a drop will
        // not be allowed.
        if (effectAllowed == nsIDragService::DRAGDROP_ACTION_UNINITIALIZED ||
            dropEffect & effectAllowed)
          action = dropEffect;

        if (action == nsIDragService::DRAGDROP_ACTION_NONE)
          dropEffect = nsIDragService::DRAGDROP_ACTION_NONE;

        // inform the drag session that a drop is allowed on this node.
        dragSession->SetDragAction(action);
        dragSession->SetCanDrop(action != nsIDragService::DRAGDROP_ACTION_NONE);

        // For now, do this only for dragover.
        // XXXsmaug dragenter needs some more work.
        if (aEvent->mMessage == eDragOver && !isChromeDoc) {
          // Someone has called preventDefault(), check whether is was on
          // content or chrome.
          dragSession->SetOnlyChromeDrop(
              !dragEvent->mDefaultPreventedOnContent);
        }
      } else if (aEvent->mMessage == eDragOver && !isChromeDoc) {
        // No one called preventDefault(), so handle drop only in chrome.
        dragSession->SetOnlyChromeDrop(true);
      }
      if (ContentChild* child = ContentChild::GetSingleton()) {
        child->SendUpdateDropEffect(action, dropEffect);
      }
      if (aEvent->HasBeenPostedToRemoteProcess()) {
        dragSession->SetCanDrop(true);
      } else if (initialDataTransfer) {
        // Now set the drop effect in the initial dataTransfer. This ensures
        // that we can get the desired drop effect in the drop event. For events
        // dispatched to content, the content process will take care of setting
        // this.
        initialDataTransfer->SetDropEffectInt(dropEffect);
      }
    } break;

    case eDrop: {
      sLastDragOverFrame = nullptr;
      ClearGlobalActiveContent(this);
      break;
    }
    case eDragExit:
      // make sure to fire the enter and exit_synth events after the
      // eDragExit event, otherwise we'll clean up too early
      GenerateDragDropEnterExit(presContext, aEvent->AsDragEvent());
      if (ContentChild* child = ContentChild::GetSingleton()) {
        // SendUpdateDropEffect to prevent nsIDragService from waiting for
        // response of forwarded dragexit event.
        child->SendUpdateDropEffect(nsIDragService::DRAGDROP_ACTION_NONE,
                                    nsIDragService::DRAGDROP_ACTION_NONE);
      }
      break;

    case eKeyUp:
      break;

    case eKeyPress: {
      WidgetKeyboardEvent* keyEvent = aEvent->AsKeyboardEvent();
      PostHandleKeyboardEvent(keyEvent, mCurrentTarget, *aStatus);
    } break;

    case eMouseEnterIntoWidget:
      if (mCurrentTarget) {
        nsCOMPtr<nsIContent> targetContent;
        mCurrentTarget->GetContentForEvent(aEvent,
                                           getter_AddRefs(targetContent));
        SetContentState(targetContent, NS_EVENT_STATE_HOVER);
      }
      break;

#ifdef XP_MACOSX
    case eMouseActivate:
      if (mCurrentTarget) {
        nsCOMPtr<nsIContent> targetContent;
        mCurrentTarget->GetContentForEvent(aEvent,
                                           getter_AddRefs(targetContent));
        if (!NodeAllowsClickThrough(targetContent)) {
          *aStatus = nsEventStatus_eConsumeNoDefault;
        }
      }
      break;
#endif

    default:
      break;
  }

  // Reset target frame to null to avoid mistargeting after reentrant event
  mCurrentTarget = nullptr;
  mCurrentTargetContent = nullptr;

  return ret;
}

TabParent* EventStateManager::GetCrossProcessTarget() {
  return IMEStateManager::GetActiveTabParent();
}

bool EventStateManager::IsTargetCrossProcess(WidgetGUIEvent* aEvent) {
  // Check to see if there is a focused, editable content in chrome,
  // in that case, do not forward IME events to content
  nsIContent* focusedContent = GetFocusedContent();
  if (focusedContent && focusedContent->IsEditable()) return false;
  return IMEStateManager::GetActiveTabParent() != nullptr;
}

void EventStateManager::NotifyDestroyPresContext(nsPresContext* aPresContext) {
  IMEStateManager::OnDestroyPresContext(aPresContext);
  if (mHoverContent) {
    // Bug 70855: Presentation is going away, possibly for a reframe.
    // Reset the hover state so that if we're recreating the presentation,
    // we won't have the old hover state still set in the new presentation,
    // as if the new presentation is resized, a new element may be hovered.
    SetContentState(nullptr, NS_EVENT_STATE_HOVER);
  }
  mPointersEnterLeaveHelper.Clear();
}

void EventStateManager::SetPresContext(nsPresContext* aPresContext) {
  mPresContext = aPresContext;
}

void EventStateManager::ClearFrameRefs(nsIFrame* aFrame) {
  if (aFrame && aFrame == mCurrentTarget) {
    mCurrentTargetContent = aFrame->GetContent();
  }
}

struct CursorImage {
  gfx::IntPoint mHotspot;
  nsCOMPtr<imgIContainer> mContainer;
  bool mEarlierCursorLoading = false;
};

// Given the event that we're processing, and the computed cursor and hotspot,
// determine whether the custom CSS cursor should be blocked (that is, not
// honored).
//
// We will not honor it all of the following are true:
//
//  * layout.cursor.block.enabled is true.
//  * the size of the custom cursor is bigger than layout.cursor.block.max-size.
//  * the bounds of the cursor would end up outside of the viewport of the
//    top-level content document.
//
// This is done in order to prevent hijacking the cursor, see bug 1445844 and
// co.
static bool ShouldBlockCustomCursor(nsPresContext* aPresContext,
                                    WidgetEvent* aEvent,
                                    const CursorImage& aCursor) {
  if (!StaticPrefs::layout_cursor_block_enabled()) {
    return false;
  }

  int32_t width = 0;
  int32_t height = 0;
  aCursor.mContainer->GetWidth(&width);
  aCursor.mContainer->GetHeight(&height);

  int32_t maxSize = StaticPrefs::layout_cursor_block_max_size();

  if (width <= maxSize && height <= maxSize) {
    return false;
  }

  // We don't want to deal with iframes, just let them do their thing unless
  // they intersect UI.
  //
  // TODO(emilio, bug 1525561): In a fission world, we should have a better way
  // to find the event coordinates relative to the content area.
  nsPresContext* topLevel =
      aPresContext->GetToplevelContentDocumentPresContext();
  if (!topLevel) {
    return false;
  }

  nsPoint point = nsLayoutUtils::GetEventCoordinatesRelativeTo(
      aEvent, topLevel->PresShell()->GetRootFrame());

  nsSize size(CSSPixel::ToAppUnits(width), CSSPixel::ToAppUnits(height));
  nsPoint hotspot(CSSPixel::ToAppUnits(aCursor.mHotspot.x),
                  CSSPixel::ToAppUnits(aCursor.mHotspot.y));

  nsRect cursorRect(point - hotspot, size);
  return !topLevel->GetVisibleArea().Contains(cursorRect);
}

static gfx::IntPoint ComputeHotspot(imgIContainer* aContainer,
                                    const Maybe<gfx::Point>& aHotspot) {
  MOZ_ASSERT(aContainer);
  // css3-ui says to use the CSS-specified hotspot if present,
  // otherwise use the intrinsic hotspot, otherwise use the top left
  // corner.
  uint32_t hotspotX, hotspotY;
  if (aHotspot) {
    int32_t imgWidth, imgHeight;
    aContainer->GetWidth(&imgWidth);
    aContainer->GetHeight(&imgHeight);

    // XXX std::max(NS_lround(x), 0)?
    hotspotX = aHotspot->x > 0.0f ? uint32_t(aHotspot->x + 0.5f) : uint32_t(0);
    if (hotspotX >= uint32_t(imgWidth)) hotspotX = imgWidth - 1;
    hotspotY = aHotspot->y > 0.0f ? uint32_t(aHotspot->y + 0.5f) : uint32_t(0);
    if (hotspotY >= uint32_t(imgHeight)) hotspotY = imgHeight - 1;
  } else {
    hotspotX = 0;
    hotspotY = 0;
    nsCOMPtr<nsIProperties> props(do_QueryInterface(aContainer));
    if (props) {
      nsCOMPtr<nsISupportsPRUint32> hotspotXWrap, hotspotYWrap;

      props->Get("hotspotX", NS_GET_IID(nsISupportsPRUint32),
                 getter_AddRefs(hotspotXWrap));
      props->Get("hotspotY", NS_GET_IID(nsISupportsPRUint32),
                 getter_AddRefs(hotspotYWrap));

      if (hotspotXWrap) hotspotXWrap->GetData(&hotspotX);
      if (hotspotYWrap) hotspotYWrap->GetData(&hotspotY);
    }
  }
  return {hotspotX, hotspotY};
}

static CursorImage ComputeCustomCursor(nsPresContext* aPresContext,
                                       WidgetEvent* aEvent,
                                       const nsIFrame& aFrame,
                                       const nsIFrame::Cursor& aCursor) {
  if (aCursor.mAllowCustomCursor == nsIFrame::AllowCustomCursorImage::No) {
    return {};
  }
  const ComputedStyle& style =
      aCursor.mStyle ? *aCursor.mStyle : *aFrame.Style();

  // If we are falling back because any cursor before us is loading, let the
  // consumer know.
  bool loading = false;
  for (const nsCursorImage& image : style.StyleUI()->mCursorImages) {
    uint32_t status;
    imgRequestProxy* req = image.GetImage();
    if (!req || NS_FAILED(req->GetImageStatus(&status))) {
      continue;
    }
    if (!(status & imgIRequest::STATUS_LOAD_COMPLETE)) {
      loading = true;
      continue;
    }
    if (status & imgIRequest::STATUS_ERROR) {
      continue;
    }
    nsCOMPtr<imgIContainer> container;
    req->GetImage(getter_AddRefs(container));
    if (!container) {
      continue;
    }
    Maybe<gfx::Point> specifiedHotspot =
        image.mHaveHotspot ? Some(gfx::Point{image.mHotspotX, image.mHotspotY})
                           : Nothing();
    gfx::IntPoint hotspot = ComputeHotspot(container, specifiedHotspot);
    CursorImage result{hotspot, std::move(container), loading};
    if (ShouldBlockCustomCursor(aPresContext, aEvent, result)) {
      continue;
    }
    // This is the one we want!
    return result;
  }
  return {{}, nullptr, loading};
}

void EventStateManager::UpdateCursor(nsPresContext* aPresContext,
                                     WidgetEvent* aEvent,
                                     nsIFrame* aTargetFrame,
                                     nsEventStatus* aStatus) {
  if (aTargetFrame && IsRemoteTarget(aTargetFrame->GetContent())) {
    return;
  }

  auto cursor = StyleCursorKind::Default;
  nsCOMPtr<imgIContainer> container;
  Maybe<gfx::IntPoint> hotspot;

  // If cursor is locked just use the locked one
  if (mLockCursor != kInvalidCursorKind) {
    cursor = mLockCursor;
  }
  // If not locked, look for correct cursor
  else if (aTargetFrame) {
    nsPoint pt =
        nsLayoutUtils::GetEventCoordinatesRelativeTo(aEvent, aTargetFrame);
    Maybe<nsIFrame::Cursor> framecursor = aTargetFrame->GetCursor(pt);
    // Avoid setting cursor when the mouse is over a windowless plugin.
    if (!framecursor) {
      if (XRE_IsContentProcess()) {
        mLastFrameConsumedSetCursor = true;
      }
      return;
    }
    // Make sure cursors get reset after the mouse leaves a
    // windowless plugin frame.
    if (mLastFrameConsumedSetCursor) {
      ClearCachedWidgetCursor(aTargetFrame);
      mLastFrameConsumedSetCursor = false;
    }

    CursorImage customCursor =
        ComputeCustomCursor(aPresContext, aEvent, *aTargetFrame, *framecursor);

    // If the current cursor is from the same frame, and it is now
    // loading some new image for the cursor, we should wait for a
    // while rather than taking its fallback cursor directly.
    if (customCursor.mEarlierCursorLoading &&
        gLastCursorSourceFrame == aTargetFrame &&
        TimeStamp::NowLoRes() - gLastCursorUpdateTime <
            TimeDuration::FromMilliseconds(kCursorLoadingTimeout)) {
      return;
    }
    cursor = framecursor->mCursor;
    container = customCursor.mContainer.forget();
    hotspot = Some(customCursor.mHotspot);
  }

  if (nsContentUtils::UseActivityCursor()) {
    // Check whether or not to show the busy cursor
    nsCOMPtr<nsIDocShell> docShell(aPresContext->GetDocShell());
    if (!docShell) return;
    auto busyFlags = docShell->GetBusyFlags();

    // Show busy cursor everywhere before page loads
    // and just replace the arrow cursor after page starts loading
    if (busyFlags & nsIDocShell::BUSY_FLAGS_BUSY &&
        (cursor == StyleCursorKind::Auto ||
         cursor == StyleCursorKind::Default)) {
      cursor = StyleCursorKind::Progress;
      container = nullptr;
    }
  }

  if (aTargetFrame) {
    SetCursor(cursor, container, hotspot, aTargetFrame->GetNearestWidget(),
              false);
    gLastCursorSourceFrame = aTargetFrame;
    gLastCursorUpdateTime = TimeStamp::NowLoRes();
  }

  if (mLockCursor != kInvalidCursorKind || StyleCursorKind::Auto != cursor) {
    *aStatus = nsEventStatus_eConsumeDoDefault;
  }
}

void EventStateManager::ClearCachedWidgetCursor(nsIFrame* aTargetFrame) {
  if (!aTargetFrame) {
    return;
  }
  nsIWidget* aWidget = aTargetFrame->GetNearestWidget();
  if (!aWidget) {
    return;
  }
  aWidget->ClearCachedCursor();
}

nsresult EventStateManager::SetCursor(StyleCursorKind aCursor,
                                      imgIContainer* aContainer,
                                      const Maybe<gfx::IntPoint>& aHotspot,
                                      nsIWidget* aWidget, bool aLockCursor) {
  EnsureDocument(mPresContext);
  NS_ENSURE_TRUE(mDocument, NS_ERROR_FAILURE);
  sMouseOverDocument = mDocument.get();

  nsCursor c;

  NS_ENSURE_TRUE(aWidget, NS_ERROR_FAILURE);
  if (aLockCursor) {
    if (StyleCursorKind::Auto != aCursor) {
      mLockCursor = aCursor;
    } else {
      // If cursor style is set to auto we unlock the cursor again.
      mLockCursor = kInvalidCursorKind;
    }
  }
  switch (aCursor) {
    default:
    case StyleCursorKind::Auto:
    case StyleCursorKind::Default:
      c = eCursor_standard;
      break;
    case StyleCursorKind::Pointer:
      c = eCursor_hyperlink;
      break;
    case StyleCursorKind::Crosshair:
      c = eCursor_crosshair;
      break;
    case StyleCursorKind::Move:
      c = eCursor_move;
      break;
    case StyleCursorKind::Text:
      c = eCursor_select;
      break;
    case StyleCursorKind::Wait:
      c = eCursor_wait;
      break;
    case StyleCursorKind::Help:
      c = eCursor_help;
      break;
    case StyleCursorKind::NResize:
      c = eCursor_n_resize;
      break;
    case StyleCursorKind::SResize:
      c = eCursor_s_resize;
      break;
    case StyleCursorKind::WResize:
      c = eCursor_w_resize;
      break;
    case StyleCursorKind::EResize:
      c = eCursor_e_resize;
      break;
    case StyleCursorKind::NwResize:
      c = eCursor_nw_resize;
      break;
    case StyleCursorKind::SeResize:
      c = eCursor_se_resize;
      break;
    case StyleCursorKind::NeResize:
      c = eCursor_ne_resize;
      break;
    case StyleCursorKind::SwResize:
      c = eCursor_sw_resize;
      break;
    case StyleCursorKind::Copy:  // CSS3
      c = eCursor_copy;
      break;
    case StyleCursorKind::Alias:
      c = eCursor_alias;
      break;
    case StyleCursorKind::ContextMenu:
      c = eCursor_context_menu;
      break;
    case StyleCursorKind::Cell:
      c = eCursor_cell;
      break;
    case StyleCursorKind::Grab:
      c = eCursor_grab;
      break;
    case StyleCursorKind::Grabbing:
      c = eCursor_grabbing;
      break;
    case StyleCursorKind::Progress:
      c = eCursor_spinning;
      break;
    case StyleCursorKind::ZoomIn:
      c = eCursor_zoom_in;
      break;
    case StyleCursorKind::ZoomOut:
      c = eCursor_zoom_out;
      break;
    case StyleCursorKind::NotAllowed:
      c = eCursor_not_allowed;
      break;
    case StyleCursorKind::ColResize:
      c = eCursor_col_resize;
      break;
    case StyleCursorKind::RowResize:
      c = eCursor_row_resize;
      break;
    case StyleCursorKind::NoDrop:
      c = eCursor_no_drop;
      break;
    case StyleCursorKind::VerticalText:
      c = eCursor_vertical_text;
      break;
    case StyleCursorKind::AllScroll:
      c = eCursor_all_scroll;
      break;
    case StyleCursorKind::NeswResize:
      c = eCursor_nesw_resize;
      break;
    case StyleCursorKind::NwseResize:
      c = eCursor_nwse_resize;
      break;
    case StyleCursorKind::NsResize:
      c = eCursor_ns_resize;
      break;
    case StyleCursorKind::EwResize:
      c = eCursor_ew_resize;
      break;
    case StyleCursorKind::None:
      c = eCursor_none;
      break;
  }

  int32_t x = aHotspot ? aHotspot->x : 0;
  int32_t y = aHotspot ? aHotspot->y : 0;
  aWidget->SetCursor(c, aContainer, x, y);
  return NS_OK;
}

class MOZ_STACK_CLASS ESMEventCB : public EventDispatchingCallback {
 public:
  explicit ESMEventCB(nsIContent* aTarget) : mTarget(aTarget) {}

  void HandleEvent(EventChainPostVisitor& aVisitor) override {
    if (aVisitor.mPresContext) {
      nsIFrame* frame = aVisitor.mPresContext->GetPrimaryFrameFor(mTarget);
      if (frame) {
        frame->HandleEvent(aVisitor.mPresContext, aVisitor.mEvent->AsGUIEvent(),
                           &aVisitor.mEventStatus);
      }
    }
  }

  nsCOMPtr<nsIContent> mTarget;
};

/*static*/
bool EventStateManager::IsHandlingUserInput() {
  return sUserInputEventDepth > 0;
}

/*static*/
bool EventStateManager::IsHandlingKeyboardInput() {
  return sUserKeyboardEventDepth > 0;
}

/*static*/
void EventStateManager::StartHandlingUserInput(EventMessage aMessage) {
  ++sUserInputEventDepth;
  ++sUserInputCounter;
  if (sUserInputEventDepth == 1) {
    sLatestUserInputStart = sHandlingInputStart = TimeStamp::Now();
  }
  if (WidgetEvent::IsKeyEventMessage(aMessage)) {
    ++sUserKeyboardEventDepth;
  }
}

/*static*/
void EventStateManager::StopHandlingUserInput(EventMessage aMessage) {
  --sUserInputEventDepth;
  if (sUserInputEventDepth == 0) {
    sHandlingInputStart = TimeStamp();
  }
  if (WidgetEvent::IsKeyEventMessage(aMessage)) {
    --sUserKeyboardEventDepth;
  }
}

static void CreateMouseOrPointerWidgetEvent(
    WidgetMouseEvent* aMouseEvent, EventMessage aMessage,
    nsIContent* aRelatedContent, nsAutoPtr<WidgetMouseEvent>& aNewEvent) {
  WidgetPointerEvent* sourcePointer = aMouseEvent->AsPointerEvent();
  if (sourcePointer) {
    AUTO_PROFILER_LABEL("CreateMouseOrPointerWidgetEvent", OTHER);

    nsAutoPtr<WidgetPointerEvent> newPointerEvent;
    newPointerEvent = new WidgetPointerEvent(aMouseEvent->IsTrusted(), aMessage,
                                             aMouseEvent->mWidget);
    newPointerEvent->mIsPrimary = sourcePointer->mIsPrimary;
    newPointerEvent->mWidth = sourcePointer->mWidth;
    newPointerEvent->mHeight = sourcePointer->mHeight;
    newPointerEvent->inputSource = sourcePointer->inputSource;
    newPointerEvent->mRelatedTarget = aRelatedContent;
    aNewEvent = newPointerEvent.forget();
  } else {
    aNewEvent =
        new WidgetMouseEvent(aMouseEvent->IsTrusted(), aMessage,
                             aMouseEvent->mWidget, WidgetMouseEvent::eReal);
    aNewEvent->mRelatedTarget = aRelatedContent;
  }
  aNewEvent->mRefPoint = aMouseEvent->mRefPoint;
  aNewEvent->mModifiers = aMouseEvent->mModifiers;
  aNewEvent->button = aMouseEvent->button;
  aNewEvent->buttons = aMouseEvent->buttons;
  aNewEvent->pressure = aMouseEvent->pressure;
  aNewEvent->mPluginEvent = aMouseEvent->mPluginEvent;
  aNewEvent->inputSource = aMouseEvent->inputSource;
  aNewEvent->pointerId = aMouseEvent->pointerId;
}

nsIFrame* EventStateManager::DispatchMouseOrPointerEvent(
    WidgetMouseEvent* aMouseEvent, EventMessage aMessage,
    nsIContent* aTargetContent, nsIContent* aRelatedContent) {
  // http://dvcs.w3.org/hg/webevents/raw-file/default/mouse-lock.html#methods
  // "[When the mouse is locked on an element...e]vents that require the concept
  // of a mouse cursor must not be dispatched (for example: mouseover,
  // mouseout).
  if (sIsPointerLocked && (aMessage == eMouseLeave || aMessage == eMouseEnter ||
                           aMessage == eMouseOver || aMessage == eMouseOut)) {
    mCurrentTargetContent = nullptr;
    nsCOMPtr<Element> pointerLockedElement =
        do_QueryReferent(EventStateManager::sPointerLockedElement);
    if (!pointerLockedElement) {
      NS_WARNING("Should have pointer locked element, but didn't.");
      return nullptr;
    }
    return mPresContext->GetPrimaryFrameFor(pointerLockedElement);
  }

  mCurrentTargetContent = nullptr;

  if (!aTargetContent) {
    return nullptr;
  }

  nsCOMPtr<nsIContent> targetContent = aTargetContent;
  nsCOMPtr<nsIContent> relatedContent = aRelatedContent;

  nsAutoPtr<WidgetMouseEvent> dispatchEvent;
  CreateMouseOrPointerWidgetEvent(aMouseEvent, aMessage, relatedContent,
                                  dispatchEvent);

  AutoWeakFrame previousTarget = mCurrentTarget;
  mCurrentTargetContent = targetContent;

  nsIFrame* targetFrame = nullptr;

  nsEventStatus status = nsEventStatus_eIgnore;
  ESMEventCB callback(targetContent);
  EventDispatcher::Dispatch(targetContent, mPresContext, dispatchEvent, nullptr,
                            &status, &callback);

  if (mPresContext) {
    // Although the primary frame was checked in event callback, it may not be
    // the same object after event dispatch and handling, so refetch it.
    targetFrame = mPresContext->GetPrimaryFrameFor(targetContent);

    // If we are entering/leaving remote content, dispatch a mouse enter/exit
    // event to the remote frame.
    if (IsRemoteTarget(targetContent)) {
      if (aMessage == eMouseOut) {
        // For remote content, send a "top-level" widget mouse exit event.
        nsAutoPtr<WidgetMouseEvent> remoteEvent;
        CreateMouseOrPointerWidgetEvent(aMouseEvent, eMouseExitFromWidget,
                                        relatedContent, remoteEvent);
        remoteEvent->mExitFrom = WidgetMouseEvent::eTopLevel;

        // mCurrentTarget is set to the new target, so we must reset it to the
        // old target and then dispatch a cross-process event. (mCurrentTarget
        // will be set back below.) HandleCrossProcessEvent will query for the
        // proper target via GetEventTarget which will return mCurrentTarget.
        mCurrentTarget = targetFrame;
        HandleCrossProcessEvent(remoteEvent, &status);
      } else if (aMessage == eMouseOver) {
        nsAutoPtr<WidgetMouseEvent> remoteEvent;
        CreateMouseOrPointerWidgetEvent(aMouseEvent, eMouseEnterIntoWidget,
                                        relatedContent, remoteEvent);
        HandleCrossProcessEvent(remoteEvent, &status);
      }
    }
  }

  mCurrentTargetContent = nullptr;
  mCurrentTarget = previousTarget;

  return targetFrame;
}

static nsIContent* FindCommonAncestor(nsIContent* aNode1, nsIContent* aNode2) {
  if (!aNode1 || !aNode2) {
    return nullptr;
  }
  return nsContentUtils::GetCommonFlattenedTreeAncestor(aNode1, aNode2);
}

class EnterLeaveDispatcher {
 public:
  EnterLeaveDispatcher(EventStateManager* aESM, nsIContent* aTarget,
                       nsIContent* aRelatedTarget,
                       WidgetMouseEvent* aMouseEvent,
                       EventMessage aEventMessage)
      : mESM(aESM), mMouseEvent(aMouseEvent), mEventMessage(aEventMessage) {
    nsPIDOMWindowInner* win =
        aTarget ? aTarget->OwnerDoc()->GetInnerWindow() : nullptr;
    if (aMouseEvent->AsPointerEvent()
            ? win && win->HasPointerEnterLeaveEventListeners()
            : win && win->HasMouseEnterLeaveEventListeners()) {
      mRelatedTarget =
          aRelatedTarget ? aRelatedTarget->FindFirstNonChromeOnlyAccessContent()
                         : nullptr;
      nsINode* commonParent = FindCommonAncestor(aTarget, aRelatedTarget);
      nsIContent* current = aTarget;
      // Note, it is ok if commonParent is null!
      while (current && current != commonParent) {
        if (!current->ChromeOnlyAccess()) {
          mTargets.AppendObject(current);
        }
        // mouseenter/leave is fired only on elements.
        current = current->GetFlattenedTreeParent();
      }
    }
  }

  void Dispatch() {
    if (mEventMessage == eMouseEnter || mEventMessage == ePointerEnter) {
      for (int32_t i = mTargets.Count() - 1; i >= 0; --i) {
        mESM->DispatchMouseOrPointerEvent(mMouseEvent, mEventMessage,
                                          mTargets[i], mRelatedTarget);
      }
    } else {
      for (int32_t i = 0; i < mTargets.Count(); ++i) {
        mESM->DispatchMouseOrPointerEvent(mMouseEvent, mEventMessage,
                                          mTargets[i], mRelatedTarget);
      }
    }
  }

  EventStateManager* mESM;
  nsCOMArray<nsIContent> mTargets;
  nsCOMPtr<nsIContent> mRelatedTarget;
  WidgetMouseEvent* mMouseEvent;
  EventMessage mEventMessage;
};

void EventStateManager::NotifyMouseOut(WidgetMouseEvent* aMouseEvent,
                                       nsIContent* aMovingInto) {
  RefPtr<OverOutElementsWrapper> wrapper = GetWrapperByEventID(aMouseEvent);

  if (!wrapper || !wrapper->mLastOverElement) return;
  // Before firing mouseout, check for recursion
  if (wrapper->mLastOverElement == wrapper->mFirstOutEventElement) return;

  if (wrapper->mLastOverFrame) {
    // if the frame is associated with a subdocument,
    // tell the subdocument that we're moving out of it
    nsSubDocumentFrame* subdocFrame =
        do_QueryFrame(wrapper->mLastOverFrame.GetFrame());
    if (subdocFrame) {
      nsIDocShell* docshell = subdocFrame->GetDocShell();
      if (docshell) {
        RefPtr<nsPresContext> presContext = docshell->GetPresContext();

        if (presContext) {
          EventStateManager* kidESM = presContext->EventStateManager();
          // Not moving into any element in this subdocument
          kidESM->NotifyMouseOut(aMouseEvent, nullptr);
        }
      }
    }
  }
  // That could have caused DOM events which could wreak havoc. Reverify
  // things and be careful.
  if (!wrapper->mLastOverElement) return;

  // Store the first mouseOut event we fire and don't refire mouseOut
  // to that element while the first mouseOut is still ongoing.
  wrapper->mFirstOutEventElement = wrapper->mLastOverElement;

  // Don't touch hover state if aMovingInto is non-null.  Caller will update
  // hover state itself, and we have optimizations for hover switching between
  // two nearby elements both deep in the DOM tree that would be defeated by
  // switching the hover state to null here.
  bool isPointer = aMouseEvent->mClass == ePointerEventClass;
  if (!aMovingInto && !isPointer) {
    // Unset :hover
    SetContentState(nullptr, NS_EVENT_STATE_HOVER);
  }

  EnterLeaveDispatcher leaveDispatcher(this, wrapper->mLastOverElement,
                                       aMovingInto, aMouseEvent,
                                       isPointer ? ePointerLeave : eMouseLeave);

  // Fire mouseout
  DispatchMouseOrPointerEvent(aMouseEvent, isPointer ? ePointerOut : eMouseOut,
                              wrapper->mLastOverElement, aMovingInto);
  leaveDispatcher.Dispatch();

  wrapper->mLastOverFrame = nullptr;
  wrapper->mLastOverElement = nullptr;

  // Turn recursion protection back off
  wrapper->mFirstOutEventElement = nullptr;
}

void EventStateManager::NotifyMouseOver(WidgetMouseEvent* aMouseEvent,
                                        nsIContent* aContent) {
  NS_ASSERTION(aContent, "Mouse must be over something");

  RefPtr<OverOutElementsWrapper> wrapper = GetWrapperByEventID(aMouseEvent);

  if (!wrapper || wrapper->mLastOverElement == aContent) return;

  // Before firing mouseover, check for recursion
  if (aContent == wrapper->mFirstOverEventElement) return;

  // Check to see if we're a subdocument and if so update the parent
  // document's ESM state to indicate that the mouse is over the
  // content associated with our subdocument.
  EnsureDocument(mPresContext);
  if (Document* parentDoc = mDocument->GetParentDocument()) {
    if (nsCOMPtr<nsIContent> docContent =
            parentDoc->FindContentForSubDocument(mDocument)) {
      if (nsIPresShell* parentShell = parentDoc->GetShell()) {
        RefPtr<EventStateManager> parentESM =
            parentShell->GetPresContext()->EventStateManager();
        parentESM->NotifyMouseOver(aMouseEvent, docContent);
      }
    }
  }
  // Firing the DOM event in the parent document could cause all kinds
  // of havoc.  Reverify and take care.
  if (wrapper->mLastOverElement == aContent) return;

  // Remember mLastOverElement as the related content for the
  // DispatchMouseOrPointerEvent() call below, since NotifyMouseOut() resets it,
  // bug 298477.
  nsCOMPtr<nsIContent> lastOverElement = wrapper->mLastOverElement;

  bool isPointer = aMouseEvent->mClass == ePointerEventClass;

  EnterLeaveDispatcher enterDispatcher(this, aContent, lastOverElement,
                                       aMouseEvent,
                                       isPointer ? ePointerEnter : eMouseEnter);

  if (!isPointer) {
    SetContentState(aContent, NS_EVENT_STATE_HOVER);
  }

  NotifyMouseOut(aMouseEvent, aContent);

  // Store the first mouseOver event we fire and don't refire mouseOver
  // to that element while the first mouseOver is still ongoing.
  wrapper->mFirstOverEventElement = aContent;

  // Fire mouseover
  wrapper->mLastOverFrame = DispatchMouseOrPointerEvent(
      aMouseEvent, isPointer ? ePointerOver : eMouseOver, aContent,
      lastOverElement);
  enterDispatcher.Dispatch();
  wrapper->mLastOverElement = aContent;

  // Turn recursion protection back off
  wrapper->mFirstOverEventElement = nullptr;
}

// Returns the center point of the window's client area. This is
// in widget coordinates, i.e. relative to the widget's top-left
// corner, not in screen coordinates, the same units that UIEvent::
// refpoint is in. It may not be the exact center of the window if
// the platform requires rounding the coordinate.
static LayoutDeviceIntPoint GetWindowClientRectCenter(nsIWidget* aWidget) {
  NS_ENSURE_TRUE(aWidget, LayoutDeviceIntPoint(0, 0));

  LayoutDeviceIntRect rect = aWidget->GetClientBounds();
  LayoutDeviceIntPoint point(rect.x + rect.width / 2, rect.y + rect.height / 2);
  int32_t round = aWidget->RoundsWidgetCoordinatesTo();
  point.x = point.x / round * round;
  point.y = point.y / round * round;
  return point - aWidget->WidgetToScreenOffset();
}

void EventStateManager::GeneratePointerEnterExit(EventMessage aMessage,
                                                 WidgetMouseEvent* aEvent) {
  if (!PointerEventHandler::IsPointerEventEnabled()) {
    return;
  }
  WidgetPointerEvent pointerEvent(*aEvent);
  pointerEvent.mMessage = aMessage;
  GenerateMouseEnterExit(&pointerEvent);
}

/* static */
void EventStateManager::UpdateLastRefPointOfMouseEvent(
    WidgetMouseEvent* aMouseEvent) {
  if (aMouseEvent->mMessage != eMouseMove &&
      aMouseEvent->mMessage != ePointerMove) {
    return;
  }

  // Mouse movement is reported on the MouseEvent.movement{X,Y} fields.
  // Movement is calculated in UIEvent::GetMovementPoint() as:
  //   previous_mousemove_mRefPoint - current_mousemove_mRefPoint.
  if (sIsPointerLocked && aMouseEvent->mWidget) {
    // The pointer is locked. If the pointer is not located at the center of
    // the window, dispatch a synthetic mousemove to return the pointer there.
    // Doing this between "real" pointer moves gives the impression that the
    // (locked) pointer can continue moving and won't stop at the screen
    // boundary. We cancel the synthetic event so that we don't end up
    // dispatching the centering move event to content.
    aMouseEvent->mLastRefPoint =
        GetWindowClientRectCenter(aMouseEvent->mWidget);

  } else if (sLastRefPoint == kInvalidRefPoint) {
    // We don't have a valid previous mousemove mRefPoint. This is either
    // the first move we've encountered, or the mouse has just re-entered
    // the application window. We should report (0,0) movement for this
    // case, so make the current and previous mRefPoints the same.
    aMouseEvent->mLastRefPoint = aMouseEvent->mRefPoint;
  } else {
    aMouseEvent->mLastRefPoint = sLastRefPoint;
  }
}

/* static */
void EventStateManager::ResetPointerToWindowCenterWhilePointerLocked(
    WidgetMouseEvent* aMouseEvent) {
  MOZ_ASSERT(sIsPointerLocked);
  if ((aMouseEvent->mMessage != eMouseMove &&
       aMouseEvent->mMessage != ePointerMove) ||
      !aMouseEvent->mWidget) {
    return;
  }

  // We generate pointermove from mousemove event, so only synthesize native
  // mouse move and update sSynthCenteringPoint by mousemove event.
  bool updateSynthCenteringPoint = aMouseEvent->mMessage == eMouseMove;

  // The pointer is locked. If the pointer is not located at the center of
  // the window, dispatch a synthetic mousemove to return the pointer there.
  // Doing this between "real" pointer moves gives the impression that the
  // (locked) pointer can continue moving and won't stop at the screen
  // boundary. We cancel the synthetic event so that we don't end up
  // dispatching the centering move event to content.
  LayoutDeviceIntPoint center = GetWindowClientRectCenter(aMouseEvent->mWidget);

  if (aMouseEvent->mRefPoint != center && updateSynthCenteringPoint) {
    // Mouse move doesn't finish at the center of the window. Dispatch a
    // synthetic native mouse event to move the pointer back to the center
    // of the window, to faciliate more movement. But first, record that
    // we've dispatched a synthetic mouse movement, so we can cancel it
    // in the other branch here.
    sSynthCenteringPoint = center;
    aMouseEvent->mWidget->SynthesizeNativeMouseMove(
        center + aMouseEvent->mWidget->WidgetToScreenOffset(), nullptr);
  } else if (aMouseEvent->mRefPoint == sSynthCenteringPoint) {
    // This is the "synthetic native" event we dispatched to re-center the
    // pointer. Cancel it so we don't expose the centering move to content.
    aMouseEvent->StopPropagation();
    // Clear sSynthCenteringPoint so we don't cancel other events
    // targeted at the center.
    if (updateSynthCenteringPoint) {
      sSynthCenteringPoint = kInvalidRefPoint;
    }
  }
}

/* static */
void EventStateManager::UpdateLastPointerPosition(
    WidgetMouseEvent* aMouseEvent) {
  if (aMouseEvent->mMessage != eMouseMove) {
    return;
  }
  sLastRefPoint = aMouseEvent->mRefPoint;
}

void EventStateManager::GenerateMouseEnterExit(WidgetMouseEvent* aMouseEvent) {
  EnsureDocument(mPresContext);
  if (!mDocument) return;

  // Hold onto old target content through the event and reset after.
  nsCOMPtr<nsIContent> targetBeforeEvent = mCurrentTargetContent;

  switch (aMouseEvent->mMessage) {
    case eMouseMove:
    case ePointerMove:
    case ePointerDown:
    case ePointerGotCapture: {
      // Get the target content target (mousemove target == mouseover target)
      nsCOMPtr<nsIContent> targetElement = GetEventTargetContent(aMouseEvent);
      if (!targetElement) {
        // We're always over the document root, even if we're only
        // over dead space in a page (whose frame is not associated with
        // any content) or in print preview dead space
        targetElement = mDocument->GetRootElement();
      }
      if (targetElement) {
        NotifyMouseOver(aMouseEvent, targetElement);
      }
    } break;
    case ePointerUp: {
      // Get the target content target (mousemove target == mouseover target)
      nsCOMPtr<nsIContent> targetElement = GetEventTargetContent(aMouseEvent);
      if (!targetElement) {
        // We're always over the document root, even if we're only
        // over dead space in a page (whose frame is not associated with
        // any content) or in print preview dead space
        targetElement = mDocument->GetRootElement();
      }
      if (targetElement) {
        RefPtr<OverOutElementsWrapper> helper =
            GetWrapperByEventID(aMouseEvent);
        if (helper) {
          helper->mLastOverElement = targetElement;
        }
        NotifyMouseOut(aMouseEvent, nullptr);
      }
    } break;
    case ePointerLeave:
    case ePointerCancel:
    case eMouseExitFromWidget: {
      // This is actually the window mouse exit or pointer leave event. We're
      // not moving into any new element.

      RefPtr<OverOutElementsWrapper> helper = GetWrapperByEventID(aMouseEvent);
      if (helper && helper->mLastOverFrame &&
          nsContentUtils::GetTopLevelWidget(aMouseEvent->mWidget) !=
              nsContentUtils::GetTopLevelWidget(
                  helper->mLastOverFrame->GetNearestWidget())) {
        // the Mouse/PointerOut event widget doesn't have same top widget with
        // mLastOverFrame, it's a spurious event for mLastOverFrame
        break;
      }

      // Reset sLastRefPoint, so that we'll know not to report any
      // movement the next time we re-enter the window.
      sLastRefPoint = kInvalidRefPoint;

      NotifyMouseOut(aMouseEvent, nullptr);
    } break;
    default:
      break;
  }

  // reset mCurretTargetContent to what it was
  mCurrentTargetContent = targetBeforeEvent;
}

OverOutElementsWrapper* EventStateManager::GetWrapperByEventID(
    WidgetMouseEvent* aEvent) {
  WidgetPointerEvent* pointer = aEvent->AsPointerEvent();
  if (!pointer) {
    MOZ_ASSERT(aEvent->AsMouseEvent() != nullptr);
    if (!mMouseEnterLeaveHelper) {
      mMouseEnterLeaveHelper = new OverOutElementsWrapper();
    }
    return mMouseEnterLeaveHelper;
  }
  return mPointersEnterLeaveHelper.LookupForAdd(pointer->pointerId)
      .OrInsert([]() { return new OverOutElementsWrapper(); });
}

/* static */
void EventStateManager::SetPointerLock(nsIWidget* aWidget,
                                       nsIContent* aElement) {
  // NOTE: aElement will be nullptr when unlocking.
  sIsPointerLocked = !!aElement;

  // Reset mouse wheel transaction
  WheelTransaction::EndTransaction();

  // Deal with DnD events
  nsCOMPtr<nsIDragService> dragService =
      do_GetService("@mozilla.org/widget/dragservice;1");

  if (sIsPointerLocked) {
    MOZ_ASSERT(aWidget, "Locking pointer requires a widget");

    // Release all pointer capture when a pointer lock is successfully applied
    // on an element.
    PointerEventHandler::ReleaseAllPointerCapture();

    // Store the last known ref point so we can reposition the pointer after
    // unlock.
    sPreLockPoint = sLastRefPoint;

    // Fire a synthetic mouse move to ensure event state is updated. We first
    // set the mouse to the center of the window, so that the mouse event
    // doesn't report any movement.
    sLastRefPoint = GetWindowClientRectCenter(aWidget);
    aWidget->SynthesizeNativeMouseMove(
        sLastRefPoint + aWidget->WidgetToScreenOffset(), nullptr);

    // Suppress DnD
    if (dragService) {
      dragService->Suppress();
    }
  } else {
    // Unlocking, so return pointer to the original position by firing a
    // synthetic mouse event. We first reset sLastRefPoint to its
    // pre-pointerlock position, so that the synthetic mouse event reports
    // no movement.
    sLastRefPoint = sPreLockPoint;
    // Reset SynthCenteringPoint to invalid so that next time we start
    // locking pointer, it has its initial value.
    sSynthCenteringPoint = kInvalidRefPoint;
    if (aWidget) {
      aWidget->SynthesizeNativeMouseMove(
          sPreLockPoint + aWidget->WidgetToScreenOffset(), nullptr);
    }

    // Unsuppress DnD
    if (dragService) {
      dragService->Unsuppress();
    }
  }
}

void EventStateManager::GenerateDragDropEnterExit(nsPresContext* aPresContext,
                                                  WidgetDragEvent* aDragEvent) {
  // Hold onto old target content through the event and reset after.
  nsCOMPtr<nsIContent> targetBeforeEvent = mCurrentTargetContent;

  switch (aDragEvent->mMessage) {
    case eDragOver: {
      // when dragging from one frame to another, events are fired in the
      // order: dragexit, dragenter, dragleave
      if (sLastDragOverFrame != mCurrentTarget) {
        // We'll need the content, too, to check if it changed separately from
        // the frames.
        nsCOMPtr<nsIContent> lastContent;
        nsCOMPtr<nsIContent> targetContent;
        mCurrentTarget->GetContentForEvent(aDragEvent,
                                           getter_AddRefs(targetContent));

        if (sLastDragOverFrame) {
          // The frame has changed but the content may not have. Check before
          // dispatching to content
          sLastDragOverFrame->GetContentForEvent(aDragEvent,
                                                 getter_AddRefs(lastContent));

          FireDragEnterOrExit(sLastDragOverFrame->PresContext(), aDragEvent,
                              eDragExit, targetContent, lastContent,
                              sLastDragOverFrame);
          nsIContent* target = sLastDragOverFrame
                                   ? sLastDragOverFrame.GetFrame()->GetContent()
                                   : nullptr;
          if (IsRemoteTarget(target)) {
            // Dragging something and moving from web content to chrome only
            // fires dragexit and dragleave to xul:browser. We have to forward
            // dragexit to sLastDragOverFrame when its content is a remote
            // target. We don't forward dragleave since it's generated from
            // dragexit.
            WidgetDragEvent remoteEvent(aDragEvent->IsTrusted(), eDragExit,
                                        aDragEvent->mWidget);
            remoteEvent.AssignDragEventData(*aDragEvent, true);
            nsEventStatus remoteStatus = nsEventStatus_eIgnore;
            HandleCrossProcessEvent(&remoteEvent, &remoteStatus);
          }
        }

        AutoWeakFrame currentTraget = mCurrentTarget;
        FireDragEnterOrExit(aPresContext, aDragEvent, eDragEnter, lastContent,
                            targetContent, currentTraget);

        if (sLastDragOverFrame) {
          FireDragEnterOrExit(sLastDragOverFrame->PresContext(), aDragEvent,
                              eDragLeave, targetContent, lastContent,
                              sLastDragOverFrame);
        }

        sLastDragOverFrame = mCurrentTarget;
      }
    } break;

    case eDragExit: {
      // This is actually the window mouse exit event.
      if (sLastDragOverFrame) {
        nsCOMPtr<nsIContent> lastContent;
        sLastDragOverFrame->GetContentForEvent(aDragEvent,
                                               getter_AddRefs(lastContent));

        RefPtr<nsPresContext> lastDragOverFramePresContext =
            sLastDragOverFrame->PresContext();
        FireDragEnterOrExit(lastDragOverFramePresContext, aDragEvent, eDragExit,
                            nullptr, lastContent, sLastDragOverFrame);
        FireDragEnterOrExit(lastDragOverFramePresContext, aDragEvent,
                            eDragLeave, nullptr, lastContent,
                            sLastDragOverFrame);

        sLastDragOverFrame = nullptr;
      }
    } break;

    default:
      break;
  }

  // reset mCurretTargetContent to what it was
  mCurrentTargetContent = targetBeforeEvent;

  // Now flush all pending notifications, for better responsiveness.
  FlushPendingEvents(aPresContext);
}

void EventStateManager::FireDragEnterOrExit(nsPresContext* aPresContext,
                                            WidgetDragEvent* aDragEvent,
                                            EventMessage aMessage,
                                            nsIContent* aRelatedTarget,
                                            nsIContent* aTargetContent,
                                            AutoWeakFrame& aTargetFrame) {
  MOZ_ASSERT(aMessage == eDragLeave || aMessage == eDragExit ||
             aMessage == eDragEnter);
  nsEventStatus status = nsEventStatus_eIgnore;
  WidgetDragEvent event(aDragEvent->IsTrusted(), aMessage, aDragEvent->mWidget);
  event.AssignDragEventData(*aDragEvent, false);
  event.mRelatedTarget = aRelatedTarget;
  mCurrentTargetContent = aTargetContent;

  if (aTargetContent != aRelatedTarget) {
    // XXX This event should still go somewhere!!
    if (aTargetContent) {
      EventDispatcher::Dispatch(aTargetContent, aPresContext, &event, nullptr,
                                &status);
    }

    // adjust the drag hover if the dragenter event was cancelled or this is a
    // drag exit
    if (status == nsEventStatus_eConsumeNoDefault || aMessage == eDragExit) {
      SetContentState((aMessage == eDragEnter) ? aTargetContent : nullptr,
                      NS_EVENT_STATE_DRAGOVER);
    }

    // collect any changes to moz cursor settings stored in the event's
    // data transfer.
    UpdateDragDataTransfer(&event);
  }

  // Finally dispatch the event to the frame
  if (aTargetFrame) aTargetFrame->HandleEvent(aPresContext, &event, &status);
}

void EventStateManager::UpdateDragDataTransfer(WidgetDragEvent* dragEvent) {
  NS_ASSERTION(dragEvent, "drag event is null in UpdateDragDataTransfer!");
  if (!dragEvent->mDataTransfer) {
    return;
  }

  nsCOMPtr<nsIDragSession> dragSession = nsContentUtils::GetDragSession();

  if (dragSession) {
    // the initial dataTransfer is the one from the dragstart event that
    // was set on the dragSession when the drag began.
    RefPtr<DataTransfer> initialDataTransfer = dragSession->GetDataTransfer();
    if (initialDataTransfer) {
      // retrieve the current moz cursor setting and save it.
      nsAutoString mozCursor;
      dragEvent->mDataTransfer->GetMozCursor(mozCursor);
      initialDataTransfer->SetMozCursor(mozCursor);
    }
  }
}

nsresult EventStateManager::SetClickCount(WidgetMouseEvent* aEvent,
                                          nsEventStatus* aStatus,
                                          nsIContent* aOverrideClickTarget) {
  nsCOMPtr<nsIContent> mouseContent = aOverrideClickTarget;
  if (!mouseContent && mCurrentTarget) {
    mCurrentTarget->GetContentForEvent(aEvent, getter_AddRefs(mouseContent));
  }
  if (mouseContent && mouseContent->IsText()) {
    nsINode* parent = mouseContent->GetFlattenedTreeParentNode();
    if (parent && parent->IsContent()) {
      mouseContent = parent->AsContent();
    }
  }

  switch (aEvent->button) {
    case WidgetMouseEvent::eLeftButton:
      if (aEvent->mMessage == eMouseDown) {
        mLastLeftMouseDownContent = mouseContent;
      } else if (aEvent->mMessage == eMouseUp) {
        aEvent->mClickTarget =
            nsContentUtils::GetCommonAncestorUnderInteractiveContent(
                mouseContent, mLastLeftMouseDownContent);
        if (aEvent->mClickTarget) {
          aEvent->mClickCount = mLClickCount;
          mLClickCount = 0;
        } else {
          aEvent->mClickCount = 0;
        }
        mLastLeftMouseDownContent = nullptr;
      }
      break;

    case WidgetMouseEvent::eMiddleButton:
      if (aEvent->mMessage == eMouseDown) {
        mLastMiddleMouseDownContent = mouseContent;
      } else if (aEvent->mMessage == eMouseUp) {
        aEvent->mClickTarget =
            nsContentUtils::GetCommonAncestorUnderInteractiveContent(
                mouseContent, mLastMiddleMouseDownContent);
        if (aEvent->mClickTarget) {
          aEvent->mClickCount = mMClickCount;
          mMClickCount = 0;
        } else {
          aEvent->mClickCount = 0;
        }
        mLastMiddleMouseDownContent = nullptr;
      }
      break;

    case WidgetMouseEvent::eRightButton:
      if (aEvent->mMessage == eMouseDown) {
        mLastRightMouseDownContent = mouseContent;
      } else if (aEvent->mMessage == eMouseUp) {
        aEvent->mClickTarget =
            nsContentUtils::GetCommonAncestorUnderInteractiveContent(
                mouseContent, mLastRightMouseDownContent);
        if (aEvent->mClickTarget) {
          aEvent->mClickCount = mRClickCount;
          mRClickCount = 0;
        } else {
          aEvent->mClickCount = 0;
        }
        mLastRightMouseDownContent = nullptr;
      }
      break;
  }

  return NS_OK;
}

// static
bool EventStateManager::EventCausesClickEvents(
    const WidgetMouseEvent& aMouseEvent) {
  if (NS_WARN_IF(aMouseEvent.mMessage != eMouseUp)) {
    return false;
  }
  // If the mouseup event is synthesized event, we don't need to dispatch
  // click events.
  if (!aMouseEvent.IsReal()) {
    return false;
  }
  // If mouse is still over same element, clickcount will be > 1.
  // If it has moved it will be zero, so no click.
  if (!aMouseEvent.mClickCount || !aMouseEvent.mClickTarget) {
    return false;
  }
  // Check that the window isn't disabled before firing a click
  // (see bug 366544).
  return !(aMouseEvent.mWidget && !aMouseEvent.mWidget->IsEnabled());
}

nsresult EventStateManager::InitAndDispatchClickEvent(
    WidgetMouseEvent* aMouseUpEvent, nsEventStatus* aStatus,
    EventMessage aMessage, nsIPresShell* aPresShell,
    nsIContent* aMouseUpContent, AutoWeakFrame aCurrentTarget,
    bool aNoContentDispatch, nsIContent* aOverrideClickTarget) {
  MOZ_ASSERT(aMouseUpEvent);
  MOZ_ASSERT(EventCausesClickEvents(*aMouseUpEvent));
  MOZ_ASSERT(aMouseUpContent || aCurrentTarget || aOverrideClickTarget);

  WidgetMouseEvent event(aMouseUpEvent->IsTrusted(), aMessage,
                         aMouseUpEvent->mWidget, WidgetMouseEvent::eReal);

  event.mRefPoint = aMouseUpEvent->mRefPoint;
  event.mClickCount = aMouseUpEvent->mClickCount;
  event.mModifiers = aMouseUpEvent->mModifiers;
  event.buttons = aMouseUpEvent->buttons;
  event.mTime = aMouseUpEvent->mTime;
  event.mTimeStamp = aMouseUpEvent->mTimeStamp;
  event.mFlags.mNoContentDispatch = aNoContentDispatch;
  event.button = aMouseUpEvent->button;
  event.pointerId = aMouseUpEvent->pointerId;
  event.inputSource = aMouseUpEvent->inputSource;
  nsIContent* target = aMouseUpContent;
  nsIFrame* targetFrame = aCurrentTarget;
  if (aOverrideClickTarget) {
    target = aOverrideClickTarget;
    targetFrame = aOverrideClickTarget->GetPrimaryFrame();
  }

  if (!target->IsInComposedDoc()) {
    return NS_OK;
  }

  // Use local event status for each click event dispatching since it'll be
  // cleared by EventStateManager::PreHandleEvent().  Therefore, dispatching
  // an event means that previous event status will be ignored.
  nsEventStatus status = nsEventStatus_eIgnore;
  nsresult rv =
      aPresShell->HandleEventWithTarget(&event, targetFrame, target, &status);
  // Copy mMultipleActionsPrevented flag from a click event to the mouseup
  // event only when it's set to true.  It may be set to true if an editor has
  // already handled it.  This is important to avoid two or more default
  // actions handled here.
  aMouseUpEvent->mFlags.mMultipleActionsPrevented |=
      event.mFlags.mMultipleActionsPrevented;
  // If current status is nsEventStatus_eConsumeNoDefault, we don't need to
  // overwrite it.
  if (*aStatus == nsEventStatus_eConsumeNoDefault) {
    return rv;
  }
  // If new status is nsEventStatus_eConsumeNoDefault or
  // nsEventStatus_eConsumeDoDefault, use it.
  if (status == nsEventStatus_eConsumeNoDefault ||
      status == nsEventStatus_eConsumeDoDefault) {
    *aStatus = status;
    return rv;
  }
  // Otherwise, keep the original status.
  return rv;
}

nsresult EventStateManager::PostHandleMouseUp(
    WidgetMouseEvent* aMouseUpEvent, nsEventStatus* aStatus,
    nsIContent* aOverrideClickTarget) {
  MOZ_ASSERT(aMouseUpEvent);
  MOZ_ASSERT(EventCausesClickEvents(*aMouseUpEvent));
  MOZ_ASSERT(aStatus);

  nsCOMPtr<nsIPresShell> presShell = mPresContext->GetPresShell();
  if (!presShell) {
    return NS_OK;
  }

  nsCOMPtr<nsIContent> clickTarget =
      do_QueryInterface(aMouseUpEvent->mClickTarget);
  NS_ENSURE_STATE(clickTarget);

  // Fire click events if the event target is still available.
  // Note that do not include the eMouseUp event's status since we ignore it
  // for compatibility with the other browsers.
  nsEventStatus status = nsEventStatus_eIgnore;
  nsresult rv = DispatchClickEvents(presShell, aMouseUpEvent, &status,
                                    clickTarget, aOverrideClickTarget);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  // Do not do anything if preceding click events are consumed.
  // Note that Chromium dispatches "paste" event and actually pates clipboard
  // text into focused editor even if the preceding click events are consumed.
  // However, this is different from our traditional behavior and does not
  // conform to DOM events.  If we need to keep compatibility with Chromium,
  // we should change it later.
  if (status == nsEventStatus_eConsumeNoDefault) {
    *aStatus = nsEventStatus_eConsumeNoDefault;
    return NS_OK;
  }

  // Handle middle click paste if it's enabled and the mouse button is middle.
  if (aMouseUpEvent->button != WidgetMouseEventBase::eMiddleButton ||
      !WidgetMouseEvent::IsMiddleClickPasteEnabled()) {
    return NS_OK;
  }
  DebugOnly<nsresult> rvIgnored =
      HandleMiddleClickPaste(presShell, aMouseUpEvent, &status, nullptr);
  NS_WARNING_ASSERTION(NS_SUCCEEDED(rvIgnored),
                       "Failed to paste for a middle click");

  // If new status is nsEventStatus_eConsumeNoDefault or
  // nsEventStatus_eConsumeDoDefault, use it.
  if (*aStatus != nsEventStatus_eConsumeNoDefault &&
      (status == nsEventStatus_eConsumeNoDefault ||
       status == nsEventStatus_eConsumeDoDefault)) {
    *aStatus = status;
  }

  // Don't return error even if middle mouse paste fails since we haven't
  // handled it here.
  return NS_OK;
}

nsresult EventStateManager::DispatchClickEvents(
    nsIPresShell* aPresShell, WidgetMouseEvent* aMouseUpEvent,
    nsEventStatus* aStatus, nsIContent* aClickTarget,
    nsIContent* aOverrideClickTarget) {
  MOZ_ASSERT(aPresShell);
  MOZ_ASSERT(aMouseUpEvent);
  MOZ_ASSERT(EventCausesClickEvents(*aMouseUpEvent));
  MOZ_ASSERT(aStatus);
  MOZ_ASSERT(aClickTarget || aOverrideClickTarget);

  bool notDispatchToContents =
      (aMouseUpEvent->button == WidgetMouseEvent::eMiddleButton ||
       aMouseUpEvent->button == WidgetMouseEvent::eRightButton);

  bool fireAuxClick = notDispatchToContents;

  AutoWeakFrame currentTarget = aClickTarget->GetPrimaryFrame();
  nsresult rv = InitAndDispatchClickEvent(
      aMouseUpEvent, aStatus, eMouseClick, aPresShell, aClickTarget,
      currentTarget, notDispatchToContents, aOverrideClickTarget);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  // Fire double click event if click count is 2.
  if (aMouseUpEvent->mClickCount == 2 && aClickTarget &&
      aClickTarget->IsInComposedDoc()) {
    rv = InitAndDispatchClickEvent(aMouseUpEvent, aStatus, eMouseDoubleClick,
                                   aPresShell, aClickTarget, currentTarget,
                                   notDispatchToContents, aOverrideClickTarget);
    if (NS_WARN_IF(NS_FAILED(rv))) {
      return rv;
    }
  }

  // Fire auxclick even if necessary.
  if (fireAuxClick && aClickTarget && aClickTarget->IsInComposedDoc()) {
    rv = InitAndDispatchClickEvent(aMouseUpEvent, aStatus, eMouseAuxClick,
                                   aPresShell, aClickTarget, currentTarget,
                                   false, aOverrideClickTarget);
    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "Failed to dispatch eMouseAuxClick");
  }

  return rv;
}

nsresult EventStateManager::HandleMiddleClickPaste(
    nsIPresShell* aPresShell, WidgetMouseEvent* aMouseEvent,
    nsEventStatus* aStatus, TextEditor* aTextEditor) {
  MOZ_ASSERT(aPresShell);
  MOZ_ASSERT(aMouseEvent);
  MOZ_ASSERT((aMouseEvent->mMessage == eMouseClick &&
              aMouseEvent->button == WidgetMouseEventBase::eMiddleButton) ||
             EventCausesClickEvents(*aMouseEvent));
  MOZ_ASSERT(aStatus);
  MOZ_ASSERT(*aStatus != nsEventStatus_eConsumeNoDefault);

  // Even if we're called twice or more for a mouse operation, we should
  // handle only once.  Although mMultipleActionsPrevented may be set to
  // true by different event handler in the future, we can use it for now.
  if (aMouseEvent->mFlags.mMultipleActionsPrevented) {
    return NS_OK;
  }
  aMouseEvent->mFlags.mMultipleActionsPrevented = true;

  RefPtr<Selection> selection;
  if (aTextEditor) {
    selection = aTextEditor->GetSelection();
    if (NS_WARN_IF(!selection)) {
      return NS_ERROR_FAILURE;
    }
  } else {
    Document* document = aPresShell->GetDocument();
    if (NS_WARN_IF(!document)) {
      return NS_ERROR_FAILURE;
    }
    nsCopySupport::GetSelectionForCopy(document, getter_AddRefs(selection));
    if (NS_WARN_IF(!selection)) {
      return NS_ERROR_FAILURE;
    }
  }

  // Move selection to the clicked point.
  nsCOMPtr<nsIContent> container;
  int32_t offset;
  nsLayoutUtils::GetContainerAndOffsetAtEvent(
      aPresShell, aMouseEvent, getter_AddRefs(container), &offset);
  if (container) {
    // XXX If readonly or disabled <input> or <textarea> in contenteditable
    //     designMode editor is clicked, the point is in the editor.
    //     However, outer HTMLEditor and Selection should handle it.
    //     So, in such case, Selection::Collapse() will fail.
    DebugOnly<nsresult> rv = selection->Collapse(container, offset);
    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
                         "Failed to collapse Selection at middle clicked");
  }

  int32_t clipboardType = nsIClipboard::kGlobalClipboard;
  nsresult rv = NS_OK;
  nsCOMPtr<nsIClipboard> clipboardService =
      do_GetService("@mozilla.org/widget/clipboard;1", &rv);
  if (NS_SUCCEEDED(rv)) {
    bool selectionSupported;
    rv = clipboardService->SupportsSelectionClipboard(&selectionSupported);
    if (NS_SUCCEEDED(rv) && selectionSupported) {
      clipboardType = nsIClipboard::kSelectionClipboard;
    }
  }

  // Fire ePaste event by ourselves since we need to dispatch "paste" event
  // even if the middle click event was consumed for compatibility with
  // Chromium.
  if (!nsCopySupport::FireClipboardEvent(ePaste, clipboardType, aPresShell,
                                         selection)) {
    *aStatus = nsEventStatus_eConsumeNoDefault;
    return NS_OK;
  }

  // Although we've fired "paste" event, there is no editor to accept the
  // clipboard content.
  if (!aTextEditor) {
    return NS_OK;
  }

  // Check if the editor is still the good target to paste.
  if (aTextEditor->Destroyed() || aTextEditor->IsReadonly() ||
      aTextEditor->IsDisabled()) {
    // XXX Should we consume the event when the editor is readonly and/or
    //     disabled?
    return NS_OK;
  }

  // The selection may have been modified during reflow.  Therefore, we
  // should adjust event target to pass IsAcceptableInputEvent().
  nsRange* range = selection->GetRangeAt(0);
  if (!range) {
    return NS_OK;
  }
  WidgetMouseEvent mouseEvent(*aMouseEvent);
  mouseEvent.mOriginalTarget = range->GetStartContainer();
  if (NS_WARN_IF(!mouseEvent.mOriginalTarget) ||
      !aTextEditor->IsAcceptableInputEvent(&mouseEvent)) {
    return NS_OK;
  }

  // If Control key is pressed, we should paste clipboard content as
  // quotation.  Otherwise, paste it as is.
  if (aMouseEvent->IsControl()) {
    DebugOnly<nsresult> rv =
        aTextEditor->PasteAsQuotationAsAction(clipboardType, false);
    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "Failed to paste as quotation");
  } else {
    DebugOnly<nsresult> rv = aTextEditor->PasteAsAction(clipboardType, false);
    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "Failed to paste");
  }
  *aStatus = nsEventStatus_eConsumeNoDefault;

  return NS_OK;
}

nsIFrame* EventStateManager::GetEventTarget() {
  nsIPresShell* shell;
  if (mCurrentTarget || !mPresContext ||
      !(shell = mPresContext->GetPresShell())) {
    return mCurrentTarget;
  }

  if (mCurrentTargetContent) {
    mCurrentTarget = mPresContext->GetPrimaryFrameFor(mCurrentTargetContent);
    if (mCurrentTarget) {
      return mCurrentTarget;
    }
  }

  nsIFrame* frame = shell->GetCurrentEventFrame();
  return (mCurrentTarget = frame);
}

already_AddRefed<nsIContent> EventStateManager::GetEventTargetContent(
    WidgetEvent* aEvent) {
  if (aEvent && (aEvent->mMessage == eFocus || aEvent->mMessage == eBlur)) {
    nsCOMPtr<nsIContent> content = GetFocusedContent();
    return content.forget();
  }

  if (mCurrentTargetContent) {
    nsCOMPtr<nsIContent> content = mCurrentTargetContent;
    return content.forget();
  }

  nsCOMPtr<nsIContent> content;

  nsIPresShell* presShell = mPresContext->GetPresShell();
  if (presShell) {
    content = presShell->GetEventTargetContent(aEvent);
  }

  // Some events here may set mCurrentTarget but not set the corresponding
  // event target in the PresShell.
  if (!content && mCurrentTarget) {
    mCurrentTarget->GetContentForEvent(aEvent, getter_AddRefs(content));
  }

  return content.forget();
}

static Element* GetLabelTarget(nsIContent* aPossibleLabel) {
  mozilla::dom::HTMLLabelElement* label =
      mozilla::dom::HTMLLabelElement::FromNode(aPossibleLabel);
  if (!label) return nullptr;

  return label->GetLabeledElement();
}

/* static */
void EventStateManager::SetFullscreenState(Element* aElement,
                                           bool aIsFullscreen) {
  DoStateChange(aElement, NS_EVENT_STATE_FULLSCREEN, aIsFullscreen);
}

/* static */
inline void EventStateManager::DoStateChange(Element* aElement,
                                             EventStates aState,
                                             bool aAddState) {
  if (aAddState) {
    aElement->AddStates(aState);
  } else {
    aElement->RemoveStates(aState);
  }
}

/* static */
inline void EventStateManager::DoStateChange(nsIContent* aContent,
                                             EventStates aState,
                                             bool aStateAdded) {
  if (aContent->IsElement()) {
    DoStateChange(aContent->AsElement(), aState, aStateAdded);
  }
}

/* static */
void EventStateManager::UpdateAncestorState(nsIContent* aStartNode,
                                            nsIContent* aStopBefore,
                                            EventStates aState,
                                            bool aAddState) {
  for (; aStartNode && aStartNode != aStopBefore;
       aStartNode = aStartNode->GetFlattenedTreeParent()) {
    // We might be starting with a non-element (e.g. a text node) and
    // if someone is doing something weird might be ending with a
    // non-element too (e.g. a document fragment)
    if (!aStartNode->IsElement()) {
      continue;
    }
    Element* element = aStartNode->AsElement();
    DoStateChange(element, aState, aAddState);
    Element* labelTarget = GetLabelTarget(element);
    if (labelTarget) {
      DoStateChange(labelTarget, aState, aAddState);
    }
  }

  if (aAddState) {
    // We might be in a situation where a node was in hover both
    // because it was hovered and because the label for it was
    // hovered, and while we stopped hovering the node the label is
    // still hovered.  Or we might have had two nested labels for the
    // same node, and while one is no longer hovered the other still
    // is.  In that situation, the label that's still hovered will be
    // aStopBefore or some ancestor of it, and the call we just made
    // to UpdateAncestorState with aAddState = false would have
    // removed the hover state from the node.  But the node should
    // still be in hover state.  To handle this situation we need to
    // keep walking up the tree and any time we find a label mark its
    // corresponding node as still in our state.
    for (; aStartNode; aStartNode = aStartNode->GetFlattenedTreeParent()) {
      if (!aStartNode->IsElement()) {
        continue;
      }

      Element* labelTarget = GetLabelTarget(aStartNode->AsElement());
      if (labelTarget && !labelTarget->State().HasState(aState)) {
        DoStateChange(labelTarget, aState, true);
      }
    }
  }
}

bool EventStateManager::SetContentState(nsIContent* aContent,
                                        EventStates aState) {
  // We manage 4 states here: ACTIVE, HOVER, DRAGOVER, URLTARGET
  // The input must be exactly one of them.
  MOZ_ASSERT(aState == NS_EVENT_STATE_ACTIVE ||
                 aState == NS_EVENT_STATE_HOVER ||
                 aState == NS_EVENT_STATE_DRAGOVER ||
                 aState == NS_EVENT_STATE_URLTARGET,
             "Unexpected state");

  nsCOMPtr<nsIContent> notifyContent1;
  nsCOMPtr<nsIContent> notifyContent2;
  bool updateAncestors;

  if (aState == NS_EVENT_STATE_HOVER || aState == NS_EVENT_STATE_ACTIVE) {
    // Hover and active are hierarchical
    updateAncestors = true;

    // check to see that this state is allowed by style. Check dragover too?
    // XXX Is this even what we want?
    if (mCurrentTarget) {
      const nsStyleUI* ui = mCurrentTarget->StyleUI();
      if (ui->mUserInput == StyleUserInput::None) {
        return false;
      }
    }

    if (aState == NS_EVENT_STATE_ACTIVE) {
      // Editable content can never become active since their default actions
      // are disabled.  Watch out for editable content in native anonymous
      // subtrees though, as they belong to text controls.
      if (aContent && aContent->IsEditable() &&
          !aContent->IsInNativeAnonymousSubtree()) {
        aContent = nullptr;
      }
      if (aContent != mActiveContent) {
        notifyContent1 = aContent;
        notifyContent2 = mActiveContent;
        mActiveContent = aContent;
      }
    } else {
      NS_ASSERTION(aState == NS_EVENT_STATE_HOVER, "How did that happen?");
      nsIContent* newHover;

      if (mPresContext->IsDynamic()) {
        newHover = aContent;
      } else {
        NS_ASSERTION(!aContent || aContent->GetComposedDoc() ==
                                      mPresContext->PresShell()->GetDocument(),
                     "Unexpected document");
        nsIFrame* frame = aContent ? aContent->GetPrimaryFrame() : nullptr;
        if (frame && nsLayoutUtils::IsViewportScrollbarFrame(frame)) {
          // The scrollbars of viewport should not ignore the hover state.
          // Because they are *not* the content of the web page.
          newHover = aContent;
        } else {
          // All contents of the web page should ignore the hover state.
          newHover = nullptr;
        }
      }

      if (newHover != mHoverContent) {
        notifyContent1 = newHover;
        notifyContent2 = mHoverContent;
        mHoverContent = newHover;
      }
    }
  } else {
    updateAncestors = false;
    if (aState == NS_EVENT_STATE_DRAGOVER) {
      if (aContent != sDragOverContent) {
        notifyContent1 = aContent;
        notifyContent2 = sDragOverContent;
        sDragOverContent = aContent;
      }
    } else if (aState == NS_EVENT_STATE_URLTARGET) {
      if (aContent != mURLTargetContent) {
        notifyContent1 = aContent;
        notifyContent2 = mURLTargetContent;
        mURLTargetContent = aContent;
      }
    }
  }

  // We need to keep track of which of notifyContent1 and notifyContent2 is
  // getting the state set and which is getting it unset.  If both are
  // non-null, then notifyContent1 is having the state set and notifyContent2
  // is having it unset.  But if one of them is null, we need to keep track of
  // the right thing for notifyContent1 explicitly.
  bool content1StateSet = true;
  if (!notifyContent1) {
    // This is ok because FindCommonAncestor wouldn't find anything
    // anyway if notifyContent1 is null.
    notifyContent1 = notifyContent2;
    notifyContent2 = nullptr;
    content1StateSet = false;
  }

  if (notifyContent1 && mPresContext) {
    EnsureDocument(mPresContext);
    if (mDocument) {
      nsAutoScriptBlocker scriptBlocker;

      if (updateAncestors) {
        nsCOMPtr<nsIContent> commonAncestor =
            FindCommonAncestor(notifyContent1, notifyContent2);
        if (notifyContent2) {
          // It's very important to first notify the state removal and
          // then the state addition, because due to labels it's
          // possible that we're removing state from some element but
          // then adding it again (say because mHoverContent changed
          // from a control to its label).
          UpdateAncestorState(notifyContent2, commonAncestor, aState, false);
        }
        UpdateAncestorState(notifyContent1, commonAncestor, aState,
                            content1StateSet);
      } else {
        if (notifyContent2) {
          DoStateChange(notifyContent2, aState, false);
        }
        DoStateChange(notifyContent1, aState, content1StateSet);
      }
    }
  }

  return true;
}

void EventStateManager::ResetLastOverForContent(
    const uint32_t& aIdx, RefPtr<OverOutElementsWrapper>& aElemWrapper,
    nsIContent* aContent) {
  if (aElemWrapper && aElemWrapper->mLastOverElement &&
      nsContentUtils::ContentIsFlattenedTreeDescendantOf(
          aElemWrapper->mLastOverElement, aContent)) {
    aElemWrapper->mLastOverElement = nullptr;
  }
}

void EventStateManager::RemoveNodeFromChainIfNeeded(EventStates aState,
                                                    nsIContent* aContentRemoved,
                                                    bool aNotify) {
  MOZ_ASSERT(aState == NS_EVENT_STATE_HOVER || aState == NS_EVENT_STATE_ACTIVE);
  if (!aContentRemoved->IsElement() ||
      !aContentRemoved->AsElement()->State().HasState(aState)) {
    return;
  }

  nsCOMPtr<nsIContent>& leaf =
      aState == NS_EVENT_STATE_HOVER ? mHoverContent : mActiveContent;

  MOZ_ASSERT(leaf);
  // XBL Likes to unbind content without notifying, thus the
  // NODE_IS_ANONYMOUS_ROOT check...
  MOZ_ASSERT(nsContentUtils::ContentIsFlattenedTreeDescendantOf(
                 leaf, aContentRemoved) ||
             leaf->SubtreeRoot()->HasFlag(NODE_IS_ANONYMOUS_ROOT));

  nsIContent* newLeaf = aContentRemoved->GetFlattenedTreeParent();
  MOZ_ASSERT_IF(newLeaf, newLeaf->IsElement() &&
                             newLeaf->AsElement()->State().HasState(aState));
  if (aNotify) {
    SetContentState(newLeaf, aState);
  } else {
    // We don't update the removed content's state here, since removing NAC
    // happens from layout and we don't really want to notify at that point or
    // what not.
    //
    // Also, NAC is not observable and NAC being removed will go away soon.
    leaf = newLeaf;
  }
  MOZ_ASSERT(leaf == newLeaf);
}

void EventStateManager::NativeAnonymousContentRemoved(nsIContent* aContent) {
  MOZ_ASSERT(aContent->IsRootOfNativeAnonymousSubtree());
  RemoveNodeFromChainIfNeeded(NS_EVENT_STATE_HOVER, aContent, false);
  RemoveNodeFromChainIfNeeded(NS_EVENT_STATE_ACTIVE, aContent, false);
}

void EventStateManager::ContentRemoved(Document* aDocument,
                                       nsIContent* aContent) {
  /*
   * Anchor and area elements when focused or hovered might make the UI to show
   * the current link. We want to make sure that the UI gets informed when they
   * are actually removed from the DOM.
   */
  if (aContent->IsAnyOfHTMLElements(nsGkAtoms::a, nsGkAtoms::area) &&
      (aContent->AsElement()->State().HasAtLeastOneOfStates(
          NS_EVENT_STATE_FOCUS | NS_EVENT_STATE_HOVER))) {
    nsGenericHTMLElement* element =
        static_cast<nsGenericHTMLElement*>(aContent);
    element->LeaveLink(
        element->GetPresContext(nsGenericHTMLElement::eForComposedDoc));
  }

  IMEStateManager::OnRemoveContent(mPresContext, aContent);

  // inform the focus manager that the content is being removed. If this
  // content is focused, the focus will be removed without firing events.
  nsFocusManager* fm = nsFocusManager::GetFocusManager();
  if (fm) fm->ContentRemoved(aDocument, aContent);

  RemoveNodeFromChainIfNeeded(NS_EVENT_STATE_HOVER, aContent, true);
  RemoveNodeFromChainIfNeeded(NS_EVENT_STATE_ACTIVE, aContent, true);

  if (sDragOverContent &&
      sDragOverContent->OwnerDoc() == aContent->OwnerDoc() &&
      nsContentUtils::ContentIsFlattenedTreeDescendantOf(sDragOverContent,
                                                         aContent)) {
    sDragOverContent = nullptr;
  }

  PointerEventHandler::ReleaseIfCaptureByDescendant(aContent);

  // See bug 292146 for why we want to null this out
  ResetLastOverForContent(0, mMouseEnterLeaveHelper, aContent);
  for (auto iter = mPointersEnterLeaveHelper.Iter(); !iter.Done();
       iter.Next()) {
    ResetLastOverForContent(iter.Key(), iter.Data(), aContent);
  }
}

bool EventStateManager::EventStatusOK(WidgetGUIEvent* aEvent) {
  return !(aEvent->mMessage == eMouseDown &&
           aEvent->AsMouseEvent()->button == WidgetMouseEvent::eLeftButton &&
           !sNormalLMouseEventInProcess);
}

//-------------------------------------------
// Access Key Registration
//-------------------------------------------
void EventStateManager::RegisterAccessKey(Element* aElement, uint32_t aKey) {
  if (aElement && mAccessKeys.IndexOf(aElement) == -1)
    mAccessKeys.AppendObject(aElement);
}

void EventStateManager::UnregisterAccessKey(Element* aElement, uint32_t aKey) {
  if (aElement) mAccessKeys.RemoveObject(aElement);
}

uint32_t EventStateManager::GetRegisteredAccessKey(Element* aElement) {
  MOZ_ASSERT(aElement);

  if (mAccessKeys.IndexOf(aElement) == -1) return 0;

  nsAutoString accessKey;
  aElement->GetAttr(kNameSpaceID_None, nsGkAtoms::accesskey, accessKey);
  return accessKey.First();
}

void EventStateManager::EnsureDocument(nsPresContext* aPresContext) {
  if (!mDocument) mDocument = aPresContext->Document();
}

void EventStateManager::FlushPendingEvents(nsPresContext* aPresContext) {
  MOZ_ASSERT(nullptr != aPresContext, "nullptr ptr");
  nsIPresShell* shell = aPresContext->GetPresShell();
  if (shell) {
    shell->FlushPendingNotifications(FlushType::InterruptibleLayout);
  }
}

nsIContent* EventStateManager::GetFocusedContent() {
  nsIFocusManager* fm = nsFocusManager::GetFocusManager();
  EnsureDocument(mPresContext);
  if (!fm || !mDocument) return nullptr;

  nsCOMPtr<nsPIDOMWindowOuter> focusedWindow;
  return nsFocusManager::GetFocusedDescendant(
      mDocument->GetWindow(), nsFocusManager::eOnlyCurrentWindow,
      getter_AddRefs(focusedWindow));
}

//-------------------------------------------------------
// Return true if the docshell is visible

bool EventStateManager::IsShellVisible(nsIDocShell* aShell) {
  NS_ASSERTION(aShell, "docshell is null");

  nsCOMPtr<nsIBaseWindow> basewin = do_QueryInterface(aShell);
  if (!basewin) return true;

  bool isVisible = true;
  basewin->GetVisibility(&isVisible);

  // We should be doing some additional checks here so that
  // we don't tab into hidden tabs of tabbrowser.  -bryner

  return isVisible;
}

nsresult EventStateManager::DoContentCommandEvent(
    WidgetContentCommandEvent* aEvent) {
  EnsureDocument(mPresContext);
  NS_ENSURE_TRUE(mDocument, NS_ERROR_FAILURE);
  nsCOMPtr<nsPIDOMWindowOuter> window(mDocument->GetWindow());
  NS_ENSURE_TRUE(window, NS_ERROR_FAILURE);

  nsCOMPtr<nsPIWindowRoot> root = window->GetTopWindowRoot();
  NS_ENSURE_TRUE(root, NS_ERROR_FAILURE);
  const char* cmd;
  switch (aEvent->mMessage) {
    case eContentCommandCut:
      cmd = "cmd_cut";
      break;
    case eContentCommandCopy:
      cmd = "cmd_copy";
      break;
    case eContentCommandPaste:
      cmd = "cmd_paste";
      break;
    case eContentCommandDelete:
      cmd = "cmd_delete";
      break;
    case eContentCommandUndo:
      cmd = "cmd_undo";
      break;
    case eContentCommandRedo:
      cmd = "cmd_redo";
      break;
    case eContentCommandPasteTransferable:
      cmd = "cmd_pasteTransferable";
      break;
    case eContentCommandLookUpDictionary:
      cmd = "cmd_lookUpDictionary";
      break;
    default:
      return NS_ERROR_NOT_IMPLEMENTED;
  }
  // If user tries to do something, user must try to do it in visible window.
  // So, let's retrieve controller of visible window.
  nsCOMPtr<nsIController> controller;
  nsresult rv =
      root->GetControllerForCommand(cmd, true, getter_AddRefs(controller));
  NS_ENSURE_SUCCESS(rv, rv);
  if (!controller) {
    // When GetControllerForCommand succeeded but there is no controller, the
    // command isn't supported.
    aEvent->mIsEnabled = false;
  } else {
    bool canDoIt;
    rv = controller->IsCommandEnabled(cmd, &canDoIt);
    NS_ENSURE_SUCCESS(rv, rv);
    aEvent->mIsEnabled = canDoIt;
    if (canDoIt && !aEvent->mOnlyEnabledCheck) {
      switch (aEvent->mMessage) {
        case eContentCommandPasteTransferable: {
          nsFocusManager* fm = nsFocusManager::GetFocusManager();
          nsIContent* focusedContent = fm ? fm->GetFocusedElement() : nullptr;
          RefPtr<TabParent> remote = TabParent::GetFrom(focusedContent);
          if (remote) {
            nsCOMPtr<nsITransferable> transferable = aEvent->mTransferable;
            IPCDataTransfer ipcDataTransfer;
            nsContentUtils::TransferableToIPCTransferable(
                transferable, &ipcDataTransfer, false, nullptr,
                remote->Manager());
            bool isPrivateData = transferable->GetIsPrivateData();
            nsCOMPtr<nsIPrincipal> requestingPrincipal =
                transferable->GetRequestingPrincipal();
            nsContentPolicyType contentPolicyType =
                transferable->GetContentPolicyType();
            remote->SendPasteTransferable(ipcDataTransfer, isPrivateData,
                                          IPC::Principal(requestingPrincipal),
                                          contentPolicyType);
            rv = NS_OK;
          } else {
            nsCOMPtr<nsICommandController> commandController =
                do_QueryInterface(controller);
            NS_ENSURE_STATE(commandController);

            RefPtr<nsCommandParams> params = new nsCommandParams();
            rv = params->SetISupports("transferable", aEvent->mTransferable);
            if (NS_WARN_IF(NS_FAILED(rv))) {
              return rv;
            }
            rv = commandController->DoCommandWithParams(cmd, params);
          }
          break;
        }

        case eContentCommandLookUpDictionary: {
          nsCOMPtr<nsICommandController> commandController =
              do_QueryInterface(controller);
          if (NS_WARN_IF(!commandController)) {
            return NS_ERROR_FAILURE;
          }

          RefPtr<nsCommandParams> params = new nsCommandParams();
          rv = params->SetInt("x", aEvent->mRefPoint.x);
          if (NS_WARN_IF(NS_FAILED(rv))) {
            return rv;
          }

          rv = params->SetInt("y", aEvent->mRefPoint.y);
          if (NS_WARN_IF(NS_FAILED(rv))) {
            return rv;
          }

          rv = commandController->DoCommandWithParams(cmd, params);
          break;
        }

        default:
          rv = controller->DoCommand(cmd);
          break;
      }
      NS_ENSURE_SUCCESS(rv, rv);
    }
  }
  aEvent->mSucceeded = true;
  return NS_OK;
}

nsresult EventStateManager::DoContentCommandScrollEvent(
    WidgetContentCommandEvent* aEvent) {
  NS_ENSURE_TRUE(mPresContext, NS_ERROR_NOT_AVAILABLE);
  nsIPresShell* ps = mPresContext->GetPresShell();
  NS_ENSURE_TRUE(ps, NS_ERROR_NOT_AVAILABLE);
  NS_ENSURE_TRUE(aEvent->mScroll.mAmount != 0, NS_ERROR_INVALID_ARG);

  nsIScrollableFrame::ScrollUnit scrollUnit;
  switch (aEvent->mScroll.mUnit) {
    case WidgetContentCommandEvent::eCmdScrollUnit_Line:
      scrollUnit = nsIScrollableFrame::LINES;
      break;
    case WidgetContentCommandEvent::eCmdScrollUnit_Page:
      scrollUnit = nsIScrollableFrame::PAGES;
      break;
    case WidgetContentCommandEvent::eCmdScrollUnit_Whole:
      scrollUnit = nsIScrollableFrame::WHOLE;
      break;
    default:
      return NS_ERROR_INVALID_ARG;
  }

  aEvent->mSucceeded = true;

  nsIScrollableFrame* sf =
      ps->GetScrollableFrameToScroll(nsIPresShell::eEither);
  aEvent->mIsEnabled =
      sf ? (aEvent->mScroll.mIsHorizontal ? WheelHandlingUtils::CanScrollOn(
                                                sf, aEvent->mScroll.mAmount, 0)
                                          : WheelHandlingUtils::CanScrollOn(
                                                sf, 0, aEvent->mScroll.mAmount))
         : false;

  if (!aEvent->mIsEnabled || aEvent->mOnlyEnabledCheck) {
    return NS_OK;
  }

  nsIntPoint pt(0, 0);
  if (aEvent->mScroll.mIsHorizontal) {
    pt.x = aEvent->mScroll.mAmount;
  } else {
    pt.y = aEvent->mScroll.mAmount;
  }

  // The caller may want synchronous scrolling.
  sf->ScrollBy(pt, scrollUnit, nsIScrollableFrame::INSTANT);
  return NS_OK;
}

void EventStateManager::SetActiveManager(EventStateManager* aNewESM,
                                         nsIContent* aContent) {
  if (sActiveESM && aNewESM != sActiveESM) {
    sActiveESM->SetContentState(nullptr, NS_EVENT_STATE_ACTIVE);
  }
  sActiveESM = aNewESM;
  if (sActiveESM && aContent) {
    sActiveESM->SetContentState(aContent, NS_EVENT_STATE_ACTIVE);
  }
}

void EventStateManager::ClearGlobalActiveContent(EventStateManager* aClearer) {
  if (aClearer) {
    aClearer->SetContentState(nullptr, NS_EVENT_STATE_ACTIVE);
    if (sDragOverContent) {
      aClearer->SetContentState(nullptr, NS_EVENT_STATE_DRAGOVER);
    }
  }
  if (sActiveESM && aClearer != sActiveESM) {
    sActiveESM->SetContentState(nullptr, NS_EVENT_STATE_ACTIVE);
  }
  sActiveESM = nullptr;
}

/******************************************************************/
/* mozilla::EventStateManager::DeltaAccumulator                   */
/******************************************************************/

void EventStateManager::DeltaAccumulator::InitLineOrPageDelta(
    nsIFrame* aTargetFrame, EventStateManager* aESM, WidgetWheelEvent* aEvent) {
  MOZ_ASSERT(aESM);
  MOZ_ASSERT(aEvent);

  // Reset if the previous wheel event is too old.
  if (!mLastTime.IsNull()) {
    TimeDuration duration = TimeStamp::Now() - mLastTime;
    if (duration.ToMilliseconds() > WheelTransaction::GetTimeoutTime()) {
      Reset();
    }
  }
  // If we have accumulated delta,  we may need to reset it.
  if (IsInTransaction()) {
    // If wheel event type is changed, reset the values.
    if (mHandlingDeltaMode != aEvent->mDeltaMode ||
        mIsNoLineOrPageDeltaDevice != aEvent->mIsNoLineOrPageDelta) {
      Reset();
    } else {
      // If the delta direction is changed, we should reset only the
      // accumulated values.
      if (mX && aEvent->mDeltaX && ((aEvent->mDeltaX > 0.0) != (mX > 0.0))) {
        mX = mPendingScrollAmountX = 0.0;
      }
      if (mY && aEvent->mDeltaY && ((aEvent->mDeltaY > 0.0) != (mY > 0.0))) {
        mY = mPendingScrollAmountY = 0.0;
      }
    }
  }

  mHandlingDeltaMode = aEvent->mDeltaMode;
  mIsNoLineOrPageDeltaDevice = aEvent->mIsNoLineOrPageDelta;

  // If it's handling neither a device that does not provide line or page deltas
  // nor delta values multiplied by prefs, we must not modify lineOrPageDelta
  // values.
  if (!mIsNoLineOrPageDeltaDevice &&
      !EventStateManager::WheelPrefs::GetInstance()
           ->NeedToComputeLineOrPageDelta(aEvent)) {
    // Set the delta values to mX and mY.  They would be used when above block
    // resets mX/mY/mPendingScrollAmountX/mPendingScrollAmountY if the direction
    // is changed.
    // NOTE: We shouldn't accumulate the delta values, it might could cause
    //       overflow even though it's not a realistic situation.
    if (aEvent->mDeltaX) {
      mX = aEvent->mDeltaX;
    }
    if (aEvent->mDeltaY) {
      mY = aEvent->mDeltaY;
    }
    mLastTime = TimeStamp::Now();
    return;
  }

  mX += aEvent->mDeltaX;
  mY += aEvent->mDeltaY;

  if (mHandlingDeltaMode == WheelEvent_Binding::DOM_DELTA_PIXEL) {
    // Records pixel delta values and init mLineOrPageDeltaX and
    // mLineOrPageDeltaY for wheel events which are caused by pixel only
    // devices.  Ignore mouse wheel transaction for computing this.  The
    // lineOrPageDelta values will be used by dispatching legacy
    // eMouseScrollEventClass (DOMMouseScroll) but not be used for scrolling
    // of default action.  The transaction should be used only for the default
    // action.
    nsIFrame* frame = aESM->ComputeScrollTarget(
        aTargetFrame, aEvent, COMPUTE_LEGACY_MOUSE_SCROLL_EVENT_TARGET);
    nsPresContext* pc =
        frame ? frame->PresContext() : aTargetFrame->PresContext();
    nsIScrollableFrame* scrollTarget = do_QueryFrame(frame);
    nsSize scrollAmount = aESM->GetScrollAmount(pc, aEvent, scrollTarget);
    nsIntSize scrollAmountInCSSPixels(
        nsPresContext::AppUnitsToIntCSSPixels(scrollAmount.width),
        nsPresContext::AppUnitsToIntCSSPixels(scrollAmount.height));

    aEvent->mLineOrPageDeltaX = RoundDown(mX) / scrollAmountInCSSPixels.width;
    aEvent->mLineOrPageDeltaY = RoundDown(mY) / scrollAmountInCSSPixels.height;

    mX -= aEvent->mLineOrPageDeltaX * scrollAmountInCSSPixels.width;
    mY -= aEvent->mLineOrPageDeltaY * scrollAmountInCSSPixels.height;
  } else {
    aEvent->mLineOrPageDeltaX = RoundDown(mX);
    aEvent->mLineOrPageDeltaY = RoundDown(mY);
    mX -= aEvent->mLineOrPageDeltaX;
    mY -= aEvent->mLineOrPageDeltaY;
  }

  mLastTime = TimeStamp::Now();
}

void EventStateManager::DeltaAccumulator::Reset() {
  mX = mY = 0.0;
  mPendingScrollAmountX = mPendingScrollAmountY = 0.0;
  mHandlingDeltaMode = UINT32_MAX;
  mIsNoLineOrPageDeltaDevice = false;
}

nsIntPoint
EventStateManager::DeltaAccumulator::ComputeScrollAmountForDefaultAction(
    WidgetWheelEvent* aEvent, const nsIntSize& aScrollAmountInDevPixels) {
  MOZ_ASSERT(aEvent);

  // If the wheel event is line scroll and the delta value is computed from
  // system settings, allow to override the system speed.
  bool allowScrollSpeedOverride =
      (!aEvent->mCustomizedByUserPrefs &&
       aEvent->mDeltaMode == WheelEvent_Binding::DOM_DELTA_LINE);
  DeltaValues acceleratedDelta =
      WheelTransaction::AccelerateWheelDelta(aEvent, allowScrollSpeedOverride);

  nsIntPoint result(0, 0);
  if (aEvent->mDeltaMode == WheelEvent_Binding::DOM_DELTA_PIXEL) {
    mPendingScrollAmountX += acceleratedDelta.deltaX;
    mPendingScrollAmountY += acceleratedDelta.deltaY;
  } else {
    mPendingScrollAmountX +=
        aScrollAmountInDevPixels.width * acceleratedDelta.deltaX;
    mPendingScrollAmountY +=
        aScrollAmountInDevPixels.height * acceleratedDelta.deltaY;
  }
  result.x = RoundDown(mPendingScrollAmountX);
  result.y = RoundDown(mPendingScrollAmountY);
  mPendingScrollAmountX -= result.x;
  mPendingScrollAmountY -= result.y;

  return result;
}

/******************************************************************/
/* mozilla::EventStateManager::WheelPrefs                         */
/******************************************************************/

// static
EventStateManager::WheelPrefs* EventStateManager::WheelPrefs::GetInstance() {
  if (!sInstance) {
    sInstance = new WheelPrefs();
  }
  return sInstance;
}

// static
void EventStateManager::WheelPrefs::Shutdown() {
  delete sInstance;
  sInstance = nullptr;
}

// static
void EventStateManager::WheelPrefs::OnPrefChanged(const char* aPrefName,
                                                  void* aClosure) {
  // forget all prefs, it's not problem for performance.
  sInstance->Reset();
  DeltaAccumulator::GetInstance()->Reset();
}

EventStateManager::WheelPrefs::WheelPrefs() {
  Reset();
  Preferences::RegisterPrefixCallback(OnPrefChanged, "mousewheel.");
  Preferences::AddBoolVarCache(&sWheelEventsEnabledOnPlugins,
                               "plugin.mousewheel.enabled", true);
  Preferences::AddBoolVarCache(&sIsAutoDirEnabled, "mousewheel.autodir.enabled",
                               true);
  Preferences::AddBoolVarCache(&sHonoursRootForAutoDir,
                               "mousewheel.autodir.honourroot", false);
}

EventStateManager::WheelPrefs::~WheelPrefs() {
  Preferences::UnregisterPrefixCallback(OnPrefChanged, "mousewheel.");
}

void EventStateManager::WheelPrefs::Reset() { memset(mInit, 0, sizeof(mInit)); }

EventStateManager::WheelPrefs::Index EventStateManager::WheelPrefs::GetIndexFor(
    const WidgetWheelEvent* aEvent) {
  if (!aEvent) {
    return INDEX_DEFAULT;
  }

  Modifiers modifiers =
      (aEvent->mModifiers & (MODIFIER_ALT | MODIFIER_CONTROL | MODIFIER_META |
                             MODIFIER_SHIFT | MODIFIER_OS));

  switch (modifiers) {
    case MODIFIER_ALT:
      return INDEX_ALT;
    case MODIFIER_CONTROL:
      return INDEX_CONTROL;
    case MODIFIER_META:
      return INDEX_META;
    case MODIFIER_SHIFT:
      return INDEX_SHIFT;
    case MODIFIER_OS:
      return INDEX_OS;
    default:
      // If two or more modifier keys are pressed, we should use default
      // settings.
      return INDEX_DEFAULT;
  }
}

void EventStateManager::WheelPrefs::GetBasePrefName(
    EventStateManager::WheelPrefs::Index aIndex, nsACString& aBasePrefName) {
  aBasePrefName.AssignLiteral("mousewheel.");
  switch (aIndex) {
    case INDEX_ALT:
      aBasePrefName.AppendLiteral("with_alt.");
      break;
    case INDEX_CONTROL:
      aBasePrefName.AppendLiteral("with_control.");
      break;
    case INDEX_META:
      aBasePrefName.AppendLiteral("with_meta.");
      break;
    case INDEX_SHIFT:
      aBasePrefName.AppendLiteral("with_shift.");
      break;
    case INDEX_OS:
      aBasePrefName.AppendLiteral("with_win.");
      break;
    case INDEX_DEFAULT:
    default:
      aBasePrefName.AppendLiteral("default.");
      break;
  }
}

void EventStateManager::WheelPrefs::Init(
    EventStateManager::WheelPrefs::Index aIndex) {
  if (mInit[aIndex]) {
    return;
  }
  mInit[aIndex] = true;

  nsAutoCString basePrefName;
  GetBasePrefName(aIndex, basePrefName);

  nsAutoCString prefNameX(basePrefName);
  prefNameX.AppendLiteral("delta_multiplier_x");
  mMultiplierX[aIndex] =
      static_cast<double>(Preferences::GetInt(prefNameX.get(), 100)) / 100;

  nsAutoCString prefNameY(basePrefName);
  prefNameY.AppendLiteral("delta_multiplier_y");
  mMultiplierY[aIndex] =
      static_cast<double>(Preferences::GetInt(prefN