layout/base/nsPresShell.cpp
author Chris Jones <jones.chris.g@gmail.com>
Wed, 07 Nov 2012 19:51:55 -0800
changeset 120600 ea85f4e3fc2de25e94235875648923f562c7252f
parent 120527 cf16f2f84efc6926cffcb4a2bb4e4585cc0d47c0
child 120723 f0ca8ef31bef6a53718c9b8f047de6d5e60d8916
permissions -rw-r--r--
Bug 806029: Have remote content drop their buffers when they're hidden. r=mattwoodrow sr=roc

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: set ts=2 sw=2 et tw=78:
 * 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/.
 *
 * This Original Code has been modified by IBM Corporation.
 * Modifications made by IBM described herein are
 * Copyright (c) International Business Machines
 * Corporation, 2000
 *
 * Modifications to Mozilla code or documentation
 * identified per MPL Section 3.3
 *
 * Date         Modified by     Description of modification
 * 05/03/2000   IBM Corp.       Observer events for reflow states
 */

/* a presentation of a document, part 2 */

#include "mozilla/dom/PBrowserChild.h"
#include "mozilla/dom/TabChild.h"
#include "mozilla/Likely.h"
#include "mozilla/Util.h"

#ifdef XP_WIN
#include "winuser.h"
#endif

#include "nsPresShell.h"
#include "nsPresContext.h"
#include "nsIContent.h"
#include "mozilla/dom/Element.h"
#include "nsIDocument.h"
#include "nsIDOMXULDocument.h"
#include "nsCSSStyleSheet.h" // XXX for UA sheet loading hack, can this go away please?
#include "nsIDOMCSSStyleSheet.h"  // for Pref-related rule management (bugs 22963,20760,31816)
#include "nsAnimationManager.h"
#include "nsINameSpaceManager.h"  // for Pref-related rule management (bugs 22963,20760,31816)
#include "nsIServiceManager.h"
#include "nsFrame.h"
#include "FrameLayerBuilder.h"
#include "nsViewManager.h"
#include "nsView.h"
#include "nsCRTGlue.h"
#include "prlog.h"
#include "prprf.h"
#include "prinrval.h"
#include "nsTArray.h"
#include "nsCOMArray.h"
#include "nsHashtable.h"
#include "nsContainerFrame.h"
#include "nsDOMEvent.h"
#include "nsHTMLParts.h"
#include "nsISelection.h"
#include "nsISelectionPrivate.h"
#include "mozilla/Selection.h"
#include "nsLayoutCID.h"
#include "nsGkAtoms.h"
#include "nsIDOMRange.h"
#include "nsIDOMDocument.h"
#include "nsIDOMNode.h"
#include "nsIDOMNodeList.h"
#include "nsIDOMElement.h"
#include "nsRange.h"
#include "nsCSSPseudoElements.h"
#include "nsCOMPtr.h"
#include "nsAutoPtr.h"
#include "nsReadableUtils.h"
#include "nsUnicharUtils.h"
#include "nsIPageSequenceFrame.h"
#include "nsCaret.h"
#include "nsIDOMHTMLDocument.h"
#include "nsIDOMXMLDocument.h"
#include "nsViewsCID.h"
#include "nsFrameManager.h"
#include "nsEventStateManager.h"
#include "nsIMEStateManager.h"
#include "nsXPCOM.h"
#include "nsISupportsPrimitives.h"
#include "nsILayoutHistoryState.h"
#include "nsILineIterator.h" // for ScrollContentIntoView
#include "nsWeakPtr.h"
#include "pldhash.h"
#include "nsDOMTouchEvent.h"
#include "nsIObserverService.h"
#include "nsIDocShell.h"        // for reflow observation
#include "nsIBaseWindow.h"
#include "nsError.h"
#include "nsLayoutUtils.h"
#include "nsCSSRendering.h"
  // for |#ifdef DEBUG| code
#include "prenv.h"
#include "nsAlgorithm.h"
#include "nsIAttribute.h"
#include "nsIGlobalHistory2.h"
#include "nsDisplayList.h"
#include "nsRegion.h"
#include "nsRenderingContext.h"
#include "nsAutoLayoutPhase.h"
#ifdef MOZ_REFLOW_PERF
#include "nsFontMetrics.h"
#endif
#include "PositionedEventTargeting.h"

#include "nsIReflowCallback.h"

#include "nsPIDOMWindow.h"
#include "nsFocusManager.h"
#include "nsNPAPIPluginInstance.h"
#include "nsIObjectFrame.h"
#include "nsIObjectLoadingContent.h"
#include "nsNetUtil.h"
#include "nsEventDispatcher.h"
#include "nsThreadUtils.h"
#include "nsStyleSheetService.h"
#include "gfxImageSurface.h"
#include "gfxContext.h"
#ifdef MOZ_MEDIA
#include "nsHTMLMediaElement.h"
#endif
#include "nsSMILAnimationController.h"
#include "SVGContentUtils.h"
#include "nsSVGUtils.h"
#include "nsSVGEffects.h"
#include "SVGFragmentIdentifier.h"

#include "nsRefreshDriver.h"

// Drag & Drop, Clipboard
#include "nsWidgetsCID.h"
#include "nsIClipboard.h"
#include "nsIClipboardHelper.h"
#include "nsIDocShellTreeItem.h"
#include "nsIURI.h"
#include "nsIScrollableFrame.h"
#include "prtime.h"
#include "prlong.h"
#include "nsIDragService.h"
#include "nsCopySupport.h"
#include "nsIDOMHTMLAnchorElement.h"
#include "nsIDOMHTMLAreaElement.h"
#include "nsIDOMHTMLLinkElement.h"
#include "nsITimer.h"
#ifdef ACCESSIBILITY
#include "nsAccessibilityService.h"
#include "mozilla/a11y/DocAccessible.h"
#ifdef DEBUG
#include "mozilla/a11y/Logging.h"
#endif
#endif

// For style data reconstruction
#include "nsStyleChangeList.h"
#include "nsCSSFrameConstructor.h"
#ifdef MOZ_XUL
#include "nsMenuFrame.h"
#include "nsTreeBodyFrame.h"
#include "nsIBoxObject.h"
#include "nsITreeBoxObject.h"
#include "nsMenuPopupFrame.h"
#include "nsITreeColumns.h"
#include "nsIDOMXULMultSelectCntrlEl.h"
#include "nsIDOMXULSelectCntrlItemEl.h"
#include "nsIDOMXULMenuListElement.h"

#endif
#include "nsPlaceholderFrame.h"
#include "nsCanvasFrame.h"

// Content viewer interfaces
#include "nsIContentViewer.h"
#include "imgIEncoder.h"
#include "gfxPlatform.h"

#include "mozilla/Preferences.h"
#include "mozilla/Telemetry.h"
#include "sampler.h"
#include "mozilla/css/ImageLoader.h"

#include "Layers.h"
#include "LayerTreeInvalidation.h"
#include "nsAsyncDOMEvent.h"

#define ANCHOR_SCROLL_FLAGS \
  (nsIPresShell::SCROLL_OVERFLOW_HIDDEN | nsIPresShell::SCROLL_NO_PARENT_FRAMES)

using namespace mozilla;
using namespace mozilla::dom;
using namespace mozilla::layers;

CapturingContentInfo nsIPresShell::gCaptureInfo =
  { false /* mAllowed */, false /* mPointerLock */, false /* mRetargetToElement */,
    false /* mPreventDrag */, nullptr /* mContent */ };
nsIContent* nsIPresShell::gKeyDownTarget;
nsInterfaceHashtable<nsUint32HashKey, nsIDOMTouch> nsIPresShell::gCaptureTouchList;
bool nsIPresShell::gPreventMouseEvents = false;

// convert a color value to a string, in the CSS format #RRGGBB
// *  - initially created for bugs 31816, 20760, 22963
static void ColorToString(nscolor aColor, nsAutoString &aString);

// RangePaintInfo is used to paint ranges to offscreen buffers
struct RangePaintInfo {
  nsRefPtr<nsRange> mRange;
  nsDisplayListBuilder mBuilder;
  nsDisplayList mList;

  // offset of builder's reference frame to the root frame
  nsPoint mRootOffset;

  RangePaintInfo(nsRange* aRange, nsIFrame* aFrame)
    : mRange(aRange), mBuilder(aFrame, nsDisplayListBuilder::PAINTING, false)
  {
    MOZ_COUNT_CTOR(RangePaintInfo);
  }

  ~RangePaintInfo()
  {
    mList.DeleteAll();
    MOZ_COUNT_DTOR(RangePaintInfo);
  }
};

#undef NOISY

// ----------------------------------------------------------------------

#ifdef DEBUG
// Set the environment variable GECKO_VERIFY_REFLOW_FLAGS to one or
// more of the following flags (comma separated) for handy debug
// output.
static uint32_t gVerifyReflowFlags;

struct VerifyReflowFlags {
  const char*    name;
  uint32_t bit;
};

static const VerifyReflowFlags gFlags[] = {
  { "verify",                VERIFY_REFLOW_ON },
  { "reflow",                VERIFY_REFLOW_NOISY },
  { "all",                   VERIFY_REFLOW_ALL },
  { "list-commands",         VERIFY_REFLOW_DUMP_COMMANDS },
  { "noisy-commands",        VERIFY_REFLOW_NOISY_RC },
  { "really-noisy-commands", VERIFY_REFLOW_REALLY_NOISY_RC },
  { "resize",                VERIFY_REFLOW_DURING_RESIZE_REFLOW },
};

#define NUM_VERIFY_REFLOW_FLAGS (sizeof(gFlags) / sizeof(gFlags[0]))

static void
ShowVerifyReflowFlags()
{
  printf("Here are the available GECKO_VERIFY_REFLOW_FLAGS:\n");
  const VerifyReflowFlags* flag = gFlags;
  const VerifyReflowFlags* limit = gFlags + NUM_VERIFY_REFLOW_FLAGS;
  while (flag < limit) {
    printf("  %s\n", flag->name);
    ++flag;
  }
  printf("Note: GECKO_VERIFY_REFLOW_FLAGS is a comma separated list of flag\n");
  printf("names (no whitespace)\n");
}
#endif

//========================================================================
//========================================================================
//========================================================================
#ifdef MOZ_REFLOW_PERF
class ReflowCountMgr;

static const char kGrandTotalsStr[] = "Grand Totals";

// Counting Class
class ReflowCounter {
public:
  ReflowCounter(ReflowCountMgr * aMgr = nullptr);
  ~ReflowCounter();

  void ClearTotals();
  void DisplayTotals(const char * aStr);
  void DisplayDiffTotals(const char * aStr);
  void DisplayHTMLTotals(const char * aStr);

  void Add()                { mTotal++;         }
  void Add(uint32_t aTotal) { mTotal += aTotal; }

  void CalcDiffInTotals();
  void SetTotalsCache();

  void SetMgr(ReflowCountMgr * aMgr) { mMgr = aMgr; }

  uint32_t GetTotal() { return mTotal; }
  
protected:
  void DisplayTotals(uint32_t aTotal, const char * aTitle);
  void DisplayHTMLTotals(uint32_t aTotal, const char * aTitle);

  uint32_t mTotal;
  uint32_t mCacheTotal;

  ReflowCountMgr * mMgr; // weak reference (don't delete)
};

// Counting Class
class IndiReflowCounter {
public:
  IndiReflowCounter(ReflowCountMgr * aMgr = nullptr)
    : mFrame(nullptr),
      mCount(0),
      mMgr(aMgr),
      mCounter(aMgr),
      mHasBeenOutput(false)
    {}
  virtual ~IndiReflowCounter() {}

  nsAutoString mName;
  nsIFrame *   mFrame;   // weak reference (don't delete)
  int32_t      mCount;

  ReflowCountMgr * mMgr; // weak reference (don't delete)

  ReflowCounter mCounter;
  bool          mHasBeenOutput;

};

//--------------------
// Manager Class
//--------------------
class ReflowCountMgr {
public:
  ReflowCountMgr();
  virtual ~ReflowCountMgr();

  void ClearTotals();
  void ClearGrandTotals();
  void DisplayTotals(const char * aStr);
  void DisplayHTMLTotals(const char * aStr);
  void DisplayDiffsInTotals(const char * aStr);

  void Add(const char * aName, nsIFrame * aFrame);
  ReflowCounter * LookUp(const char * aName);

  void PaintCount(const char *aName, nsRenderingContext* aRenderingContext,
                  nsPresContext *aPresContext, nsIFrame *aFrame,
                  const nsPoint &aOffset, uint32_t aColor);

  FILE * GetOutFile() { return mFD; }

  PLHashTable * GetIndiFrameHT() { return mIndiFrameCounts; }

  void SetPresContext(nsPresContext * aPresContext) { mPresContext = aPresContext; } // weak reference
  void SetPresShell(nsIPresShell* aPresShell) { mPresShell= aPresShell; } // weak reference

  void SetDumpFrameCounts(bool aVal)         { mDumpFrameCounts = aVal; }
  void SetDumpFrameByFrameCounts(bool aVal)  { mDumpFrameByFrameCounts = aVal; }
  void SetPaintFrameCounts(bool aVal)        { mPaintFrameByFrameCounts = aVal; }

  bool IsPaintingFrameCounts() { return mPaintFrameByFrameCounts; }

protected:
  void DisplayTotals(uint32_t aTotal, uint32_t * aDupArray, char * aTitle);
  void DisplayHTMLTotals(uint32_t aTotal, uint32_t * aDupArray, char * aTitle);

  static int RemoveItems(PLHashEntry *he, int i, void *arg);
  static int RemoveIndiItems(PLHashEntry *he, int i, void *arg);
  void CleanUp();

  // stdout Output Methods
  static int DoSingleTotal(PLHashEntry *he, int i, void *arg);
  static int DoSingleIndi(PLHashEntry *he, int i, void *arg);

  void DoGrandTotals();
  void DoIndiTotalsTree();

  // HTML Output Methods
  static int DoSingleHTMLTotal(PLHashEntry *he, int i, void *arg);
  void DoGrandHTMLTotals();

  // Zero Out the Totals
  static int DoClearTotals(PLHashEntry *he, int i, void *arg);

  // Displays the Diff Totals
  static int DoDisplayDiffTotals(PLHashEntry *he, int i, void *arg);

  PLHashTable * mCounts;
  PLHashTable * mIndiFrameCounts;
  FILE * mFD;
  
  bool mDumpFrameCounts;
  bool mDumpFrameByFrameCounts;
  bool mPaintFrameByFrameCounts;

  bool mCycledOnce;

  // Root Frame for Individual Tracking
  nsPresContext * mPresContext;
  nsIPresShell*    mPresShell;

  // ReflowCountMgr gReflowCountMgr;
};
#endif
//========================================================================

// comment out to hide caret
#define SHOW_CARET

// The upper bound on the amount of time to spend reflowing, in
// microseconds.  When this bound is exceeded and reflow commands are
// still queued up, a reflow event is posted.  The idea is for reflow
// to not hog the processor beyond the time specifed in
// gMaxRCProcessingTime.  This data member is initialized from the
// layout.reflow.timeslice pref.
#define NS_MAX_REFLOW_TIME    1000000
static int32_t gMaxRCProcessingTime = -1;

struct nsCallbackEventRequest
{
  nsIReflowCallback* callback;
  nsCallbackEventRequest* next;
};

// ----------------------------------------------------------------------------
#define ASSERT_REFLOW_SCHEDULED_STATE()                                       \
  NS_ASSERTION(mReflowScheduled ==                                            \
                 GetPresContext()->RefreshDriver()->                          \
                   IsLayoutFlushObserver(this), "Unexpected state")

class nsAutoCauseReflowNotifier
{
public:
  nsAutoCauseReflowNotifier(PresShell* aShell)
    : mShell(aShell)
  {
    mShell->WillCauseReflow();
  }
  ~nsAutoCauseReflowNotifier()
  {
    // This check should not be needed. Currently the only place that seem
    // to need it is the code that deals with bug 337586.
    if (!mShell->mHaveShutDown) {
      mShell->DidCauseReflow();
    }
    else {
      nsContentUtils::RemoveScriptBlocker();
    }
  }

  PresShell* mShell;
};

class NS_STACK_CLASS nsPresShellEventCB : public nsDispatchingCallback
{
public:
  nsPresShellEventCB(PresShell* aPresShell) : mPresShell(aPresShell) {}

  virtual void HandleEvent(nsEventChainPostVisitor& aVisitor)
  {
    if (aVisitor.mPresContext && aVisitor.mEvent->eventStructType != NS_EVENT) {
      if (aVisitor.mEvent->message == NS_MOUSE_BUTTON_DOWN ||
          aVisitor.mEvent->message == NS_MOUSE_BUTTON_UP) {
        // Mouse-up and mouse-down events call nsFrame::HandlePress/Release
        // which call GetContentOffsetsFromPoint which requires up-to-date layout.
        // Bring layout up-to-date now so that GetCurrentEventFrame() below
        // will return a real frame and we don't have to worry about
        // destroying it by flushing later.
        mPresShell->FlushPendingNotifications(Flush_Layout);
      } else if (aVisitor.mEvent->message == NS_WHEEL_WHEEL &&
                 aVisitor.mEventStatus != nsEventStatus_eConsumeNoDefault) {
        nsIFrame* frame = mPresShell->GetCurrentEventFrame();
        if (frame) {
          // chrome (including addons) should be able to know if content
          // handles both D3E "wheel" event and legacy mouse scroll events.
          // We should dispatch legacy mouse events before dispatching the
          // "wheel" event into system group.
          nsRefPtr<nsEventStateManager> esm =
            aVisitor.mPresContext->EventStateManager();
          esm->DispatchLegacyMouseScrollEvents(frame,
                 static_cast<widget::WheelEvent*>(aVisitor.mEvent),
                 &aVisitor.mEventStatus);
        }
      }
      nsIFrame* frame = mPresShell->GetCurrentEventFrame();
      if (!frame &&
          (aVisitor.mEvent->message == NS_MOUSE_BUTTON_UP ||
           aVisitor.mEvent->message == NS_TOUCH_END)) {
        // Redirect BUTTON_UP and TOUCH_END events to the root frame to ensure
        // that capturing is released.
        frame = mPresShell->GetRootFrame();
      }
      if (frame) {
        frame->HandleEvent(aVisitor.mPresContext,
                           (nsGUIEvent*) aVisitor.mEvent,
                           &aVisitor.mEventStatus);
      }
    }
  }

  nsRefPtr<PresShell> mPresShell;
};

class nsBeforeFirstPaintDispatcher : public nsRunnable
{
public:
  nsBeforeFirstPaintDispatcher(nsIDocument* aDocument)
  : mDocument(aDocument) {}

  // Fires the "before-first-paint" event so that interested parties (right now, the
  // mobile browser) are aware of it.
  NS_IMETHOD Run()
  {
    nsCOMPtr<nsIObserverService> observerService =
      mozilla::services::GetObserverService();
    if (observerService) {
      observerService->NotifyObservers(mDocument, "before-first-paint", NULL);
    }
    return NS_OK;
  }

private:
  nsCOMPtr<nsIDocument> mDocument;
};

bool PresShell::sDisableNonTestMouseEvents = false;

#ifdef PR_LOGGING
PRLogModuleInfo* PresShell::gLog;
#endif

#ifdef DEBUG
static void
VerifyStyleTree(nsPresContext* aPresContext, nsFrameManager* aFrameManager)
{
  if (nsFrame::GetVerifyStyleTreeEnable()) {
    nsIFrame* rootFrame = aFrameManager->GetRootFrame();
    aFrameManager->DebugVerifyStyleTree(rootFrame);
  }
}
#define VERIFY_STYLE_TREE ::VerifyStyleTree(mPresContext, mFrameConstructor)
#else
#define VERIFY_STYLE_TREE
#endif

static bool gVerifyReflowEnabled;

bool
nsIPresShell::GetVerifyReflowEnable()
{
#ifdef DEBUG
  static bool firstTime = true;
  if (firstTime) {
    firstTime = false;
    char* flags = PR_GetEnv("GECKO_VERIFY_REFLOW_FLAGS");
    if (flags) {
      bool error = false;

      for (;;) {
        char* comma = PL_strchr(flags, ',');
        if (comma)
          *comma = '\0';

        bool found = false;
        const VerifyReflowFlags* flag = gFlags;
        const VerifyReflowFlags* limit = gFlags + NUM_VERIFY_REFLOW_FLAGS;
        while (flag < limit) {
          if (PL_strcasecmp(flag->name, flags) == 0) {
            gVerifyReflowFlags |= flag->bit;
            found = true;
            break;
          }
          ++flag;
        }

        if (! found)
          error = true;

        if (! comma)
          break;

        *comma = ',';
        flags = comma + 1;
      }

      if (error)
        ShowVerifyReflowFlags();
    }

    if (VERIFY_REFLOW_ON & gVerifyReflowFlags) {
      gVerifyReflowEnabled = true;

      printf("Note: verifyreflow is enabled");
      if (VERIFY_REFLOW_NOISY & gVerifyReflowFlags) {
        printf(" (noisy)");
      }
      if (VERIFY_REFLOW_ALL & gVerifyReflowFlags) {
        printf(" (all)");
      }
      if (VERIFY_REFLOW_DUMP_COMMANDS & gVerifyReflowFlags) {
        printf(" (show reflow commands)");
      }
      if (VERIFY_REFLOW_NOISY_RC & gVerifyReflowFlags) {
        printf(" (noisy reflow commands)");
        if (VERIFY_REFLOW_REALLY_NOISY_RC & gVerifyReflowFlags) {
          printf(" (REALLY noisy reflow commands)");
        }
      }
      printf("\n");
    }
  }
#endif
  return gVerifyReflowEnabled;
}
  
void 
PresShell::AddInvalidateHiddenPresShellObserver(nsRefreshDriver *aDriver)
{
  if (!mHiddenInvalidationObserverRefreshDriver && !mIsDestroying && !mHaveShutDown) {
    aDriver->AddPresShellToInvalidateIfHidden(this);
    mHiddenInvalidationObserverRefreshDriver = aDriver;
  }
}

void
nsIPresShell::InvalidatePresShellIfHidden()
{
  if (!IsVisible() && mPresContext) {
    mPresContext->NotifyInvalidation(0);
  }
  mHiddenInvalidationObserverRefreshDriver = nullptr;
}

void
nsIPresShell::SetVerifyReflowEnable(bool aEnabled)
{
  gVerifyReflowEnabled = aEnabled;
}

/* virtual */ void
nsIPresShell::AddWeakFrameExternal(nsWeakFrame* aWeakFrame)
{
  AddWeakFrameInternal(aWeakFrame);
}

void
nsIPresShell::AddWeakFrameInternal(nsWeakFrame* aWeakFrame)
{
  if (aWeakFrame->GetFrame()) {
    aWeakFrame->GetFrame()->AddStateBits(NS_FRAME_EXTERNAL_REFERENCE);
  }
  aWeakFrame->SetPreviousWeakFrame(mWeakFrames);
  mWeakFrames = aWeakFrame;
}

/* virtual */ void
nsIPresShell::RemoveWeakFrameExternal(nsWeakFrame* aWeakFrame)
{
  RemoveWeakFrameInternal(aWeakFrame);
}

void
nsIPresShell::RemoveWeakFrameInternal(nsWeakFrame* aWeakFrame)
{
  if (mWeakFrames == aWeakFrame) {
    mWeakFrames = aWeakFrame->GetPreviousWeakFrame();
    return;
  }
  nsWeakFrame* nextWeak = mWeakFrames;
  while (nextWeak && nextWeak->GetPreviousWeakFrame() != aWeakFrame) {
    nextWeak = nextWeak->GetPreviousWeakFrame();
  }
  if (nextWeak) {
    nextWeak->SetPreviousWeakFrame(aWeakFrame->GetPreviousWeakFrame());
  }
}

already_AddRefed<nsFrameSelection>
nsIPresShell::FrameSelection()
{
  NS_IF_ADDREF(mSelection);
  return mSelection;
}

//----------------------------------------------------------------------

nsresult
NS_NewPresShell(nsIPresShell** aInstancePtrResult)
{
  NS_PRECONDITION(nullptr != aInstancePtrResult, "null ptr");

  if (!aInstancePtrResult)
    return NS_ERROR_NULL_POINTER;

  *aInstancePtrResult = new PresShell();

  NS_ADDREF(*aInstancePtrResult);
  return NS_OK;
}

static bool sSynthMouseMove = true;

PresShell::PresShell()
  : mMouseLocation(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE)
{
  mSelection = nullptr;
#ifdef MOZ_REFLOW_PERF
  mReflowCountMgr = new ReflowCountMgr();
  mReflowCountMgr->SetPresContext(mPresContext);
  mReflowCountMgr->SetPresShell(this);
#endif
#ifdef PR_LOGGING
  if (! gLog)
    gLog = PR_NewLogModule("PresShell");
#endif
  mSelectionFlags = nsISelectionDisplay::DISPLAY_TEXT | nsISelectionDisplay::DISPLAY_IMAGES;
  mIsThemeSupportDisabled = false;
  mIsActive = true;
  // FIXME/bug 735029: find a better solution to this problem
#ifdef MOZ_ANDROID_OMTC
  // The java pan/zoom code uses this to mean approximately "request a
  // reset of pan/zoom state" which doesn't necessarily correspond
  // with the first paint of content.
  mIsFirstPaint = false;
#else
  mIsFirstPaint = true;
#endif
  mFrozen = false;
#ifdef DEBUG
  mPresArenaAllocCount = 0;
#endif
  mRenderFlags = 0;
  mXResolution = 1.0;
  mYResolution = 1.0;
  mViewportOverridden = false;

  mScrollPositionClampingScrollPortSizeSet = false;

  mMaxLineBoxWidth = 0;

  static bool addedSynthMouseMove = false;
  if (!addedSynthMouseMove) {
    Preferences::AddBoolVarCache(&sSynthMouseMove,
                                 "layout.reflow.synthMouseMove", true);
    addedSynthMouseMove = true;
  }
}

NS_IMPL_ISUPPORTS7(PresShell, nsIPresShell, nsIDocumentObserver,
                   nsISelectionController,
                   nsISelectionDisplay, nsIObserver, nsISupportsWeakReference,
                   nsIMutationObserver)

PresShell::~PresShell()
{
  if (!mHaveShutDown) {
    NS_NOTREACHED("Someone did not call nsIPresShell::destroy");
    Destroy();
  }

  NS_ASSERTION(mCurrentEventContentStack.Count() == 0,
               "Huh, event content left on the stack in pres shell dtor!");
  NS_ASSERTION(mFirstCallbackEventRequest == nullptr &&
               mLastCallbackEventRequest == nullptr,
               "post-reflow queues not empty.  This means we're leaking");

#ifdef DEBUG
  MOZ_ASSERT(mPresArenaAllocCount == 0,
             "Some pres arena objects were not freed");
#endif

  delete mStyleSet;
  delete mFrameConstructor;

  mCurrentEventContent = nullptr;

  NS_IF_RELEASE(mPresContext);
  NS_IF_RELEASE(mDocument);
  NS_IF_RELEASE(mSelection);
}

/**
 * Initialize the presentation shell. Create view manager and style
 * manager.
 */
nsresult
PresShell::Init(nsIDocument* aDocument,
                nsPresContext* aPresContext,
                nsIViewManager* aViewManager,
                nsStyleSet* aStyleSet,
                nsCompatibility aCompatMode)
{
  NS_PRECONDITION(nullptr != aDocument, "null ptr");
  NS_PRECONDITION(nullptr != aPresContext, "null ptr");
  NS_PRECONDITION(nullptr != aViewManager, "null ptr");
  nsresult result;

  if ((nullptr == aDocument) || (nullptr == aPresContext) ||
      (nullptr == aViewManager)) {
    return NS_ERROR_NULL_POINTER;
  }
  if (mDocument) {
    NS_WARNING("PresShell double init'ed");
    return NS_ERROR_ALREADY_INITIALIZED;
  }

  mFramesToDirty.Init();

  mDocument = aDocument;
  NS_ADDREF(mDocument);
  mViewManager = aViewManager;

  // Create our frame constructor.
  mFrameConstructor = new nsCSSFrameConstructor(mDocument, this);

  mFrameManager = mFrameConstructor;

  // The document viewer owns both view manager and pres shell.
  mViewManager->SetPresShell(this);

  // Bind the context to the presentation shell.
  mPresContext = aPresContext;
  NS_ADDREF(mPresContext);
  aPresContext->SetShell(this);

  // Now we can initialize the style set.
  result = aStyleSet->Init(aPresContext);
  NS_ENSURE_SUCCESS(result, result);

  // From this point on, any time we return an error we need to make
  // sure to null out mStyleSet first, since an error return from this
  // method will cause the caller to delete the style set, so we don't
  // want to delete it in our destructor.
  mStyleSet = aStyleSet;

  // Notify our prescontext that it now has a compatibility mode.  Note that
  // this MUST happen after we set up our style set but before we create any
  // frames.
  mPresContext->CompatibilityModeChanged();

  // setup the preference style rules (no forced reflow), and do it
  // before creating any frames.
  SetPreferenceStyleRules(false);

  NS_ADDREF(mSelection = new nsFrameSelection());

  // Create and initialize the frame manager
  // XXXjwatt it would be better if we did this right after creating
  // mFrameConstructor, since the frame constructor and frame manager
  // are now the same object.
  result =  mFrameConstructor->Init(mStyleSet);
  if (NS_FAILED(result)) {
    NS_WARNING("Frame manager initialization failed");
    mStyleSet = nullptr;
    return result;
  }

  mSelection->Init(this, nullptr);

  // Important: this has to happen after the selection has been set up
#ifdef SHOW_CARET
  // make the caret
  mCaret = new nsCaret();
  mCaret->Init(this);
  mOriginalCaret = mCaret;

  //SetCaretEnabled(true);       // make it show in browser windows
#endif  
  //set up selection to be displayed in document
  // Don't enable selection for print media
  nsPresContext::nsPresContextType type = aPresContext->Type();
  if (type != nsPresContext::eContext_PrintPreview &&
      type != nsPresContext::eContext_Print)
    SetDisplaySelection(nsISelectionController::SELECTION_DISABLED);
  
  if (gMaxRCProcessingTime == -1) {
    gMaxRCProcessingTime =
      Preferences::GetInt("layout.reflow.timeslice", NS_MAX_REFLOW_TIME);
  }

  {
    nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
    if (os) {
      os->AddObserver(this, "agent-sheet-added", false);
      os->AddObserver(this, "user-sheet-added", false);
      os->AddObserver(this, "author-sheet-added", false);
      os->AddObserver(this, "agent-sheet-removed", false);
      os->AddObserver(this, "user-sheet-removed", false);
      os->AddObserver(this, "author-sheet-removed", false);
#ifdef MOZ_XUL
      os->AddObserver(this, "chrome-flush-skin-caches", false);
#endif
    }
  }

#ifdef MOZ_REFLOW_PERF
    if (mReflowCountMgr) {
      bool paintFrameCounts =
        Preferences::GetBool("layout.reflow.showframecounts");

      bool dumpFrameCounts =
        Preferences::GetBool("layout.reflow.dumpframecounts");

      bool dumpFrameByFrameCounts =
        Preferences::GetBool("layout.reflow.dumpframebyframecounts");

      mReflowCountMgr->SetDumpFrameCounts(dumpFrameCounts);
      mReflowCountMgr->SetDumpFrameByFrameCounts(dumpFrameByFrameCounts);
      mReflowCountMgr->SetPaintFrameCounts(paintFrameCounts);
    }
#endif

  if (mDocument->HasAnimationController()) {
    nsSMILAnimationController* animCtrl = mDocument->GetAnimationController();
    animCtrl->NotifyRefreshDriverCreated(GetPresContext()->RefreshDriver());
  }

  // Get our activeness from the docShell.
  QueryIsActive();

  // Setup our font inflation preferences.
  SetupFontInflation();

  return NS_OK;
}

void
PresShell::Destroy()
{
  NS_ASSERTION(!nsContentUtils::IsSafeToRunScript(),
    "destroy called on presshell while scripts not blocked");

#ifdef MOZ_REFLOW_PERF
  DumpReflows();
  if (mReflowCountMgr) {
    delete mReflowCountMgr;
    mReflowCountMgr = nullptr;
  }
#endif

  if (mHaveShutDown)
    return;

#ifdef ACCESSIBILITY
  if (mDocAccessible) {
#ifdef DEBUG
    if (a11y::logging::IsEnabled(a11y::logging::eDocDestroy))
      a11y::logging::DocDestroy("presshell destroyed", mDocument);
#endif

    mDocAccessible->Shutdown();
    mDocAccessible = nullptr;
  }
#endif // ACCESSIBILITY

  MaybeReleaseCapturingContent();

  if (gKeyDownTarget && gKeyDownTarget->OwnerDoc() == mDocument) {
    NS_RELEASE(gKeyDownTarget);
  }

  if (mContentToScrollTo) {
    mContentToScrollTo->DeleteProperty(nsGkAtoms::scrolling);
    mContentToScrollTo = nullptr;
  }

  if (mPresContext) {
    // We need to notify the destroying the nsPresContext to ESM for
    // suppressing to use from ESM.
    mPresContext->EventStateManager()->NotifyDestroyPresContext(mPresContext);
  }

  {
    nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
    if (os) {
      os->RemoveObserver(this, "agent-sheet-added");
      os->RemoveObserver(this, "user-sheet-added");
      os->RemoveObserver(this, "author-sheet-added");
      os->RemoveObserver(this, "agent-sheet-removed");
      os->RemoveObserver(this, "user-sheet-removed");
      os->RemoveObserver(this, "author-sheet-removed");
#ifdef MOZ_XUL
      os->RemoveObserver(this, "chrome-flush-skin-caches");
#endif
    }
  }

  // If our paint suppression timer is still active, kill it.
  if (mPaintSuppressionTimer) {
    mPaintSuppressionTimer->Cancel();
    mPaintSuppressionTimer = nullptr;
  }

  // Same for our reflow continuation timer
  if (mReflowContinueTimer) {
    mReflowContinueTimer->Cancel();
    mReflowContinueTimer = nullptr;
  }

  mSynthMouseMoveEvent.Revoke();

  if (mCaret) {
    mCaret->Terminate();
    mCaret = nullptr;
  }

  if (mSelection) {
    mSelection->DisconnectFromPresShell();
  }

  // release our pref style sheet, if we have one still
  ClearPreferenceStyleRules();

  mIsDestroying = true;

  // We can't release all the event content in
  // mCurrentEventContentStack here since there might be code on the
  // stack that will release the event content too. Double release
  // bad!

  // The frames will be torn down, so remove them from the current
  // event frame stack (since they'd be dangling references if we'd
  // leave them in) and null out the mCurrentEventFrame pointer as
  // well.

  mCurrentEventFrame = nullptr;

  int32_t i, count = mCurrentEventFrameStack.Length();
  for (i = 0; i < count; i++) {
    mCurrentEventFrameStack[i] = nullptr;
  }

  mFramesToDirty.Clear();

  if (mViewManager) {
    // Clear the view manager's weak pointer back to |this| in case it
    // was leaked.
    mViewManager->SetPresShell(nullptr);
    mViewManager = nullptr;
  }

  mStyleSet->BeginShutdown(mPresContext);
  nsRefreshDriver* rd = GetPresContext()->RefreshDriver();

  // This shell must be removed from the document before the frame
  // hierarchy is torn down to avoid finding deleted frames through
  // this presshell while the frames are being torn down
  if (mDocument) {
    NS_ASSERTION(mDocument->GetShell() == this, "Wrong shell?");
    mDocument->DeleteShell();

    if (mDocument->HasAnimationController()) {
      mDocument->GetAnimationController()->NotifyRefreshDriverDestroying(rd);
    }
  }

  // Revoke any pending events.  We need to do this and cancel pending reflows
  // before we destroy the frame manager, since apparently frame destruction
  // sometimes spins the event queue when plug-ins are involved(!).
  rd->RemoveLayoutFlushObserver(this);
  if (mHiddenInvalidationObserverRefreshDriver) {
    mHiddenInvalidationObserverRefreshDriver->RemovePresShellToInvalidateIfHidden(this);
  }

  rd->RevokeViewManagerFlush();

  mResizeEvent.Revoke();
  if (mAsyncResizeTimerIsActive) {
    mAsyncResizeEventTimer->Cancel();
    mAsyncResizeTimerIsActive = false;
  }

  CancelAllPendingReflows();
  CancelPostedReflowCallbacks();

  // Destroy the frame manager. This will destroy the frame hierarchy
  mFrameConstructor->WillDestroyFrameTree();

  // Destroy all frame properties (whose destruction was suppressed
  // while destroying the frame tree, but which might contain more
  // frames within the properties.
  if (mPresContext) {
    // Clear out the prescontext's property table -- since our frame tree is
    // now dead, we shouldn't be looking up any more properties in that table.
    // We want to do this before we call SetShell() on the prescontext, so
    // property destructors can usefully call GetPresShell() on the
    // prescontext.
    mPresContext->PropertyTable()->DeleteAll();
  }


  NS_WARN_IF_FALSE(!mWeakFrames, "Weak frames alive after destroying FrameManager");
  while (mWeakFrames) {
    mWeakFrames->Clear(this);
  }

  // Let the style set do its cleanup.
  mStyleSet->Shutdown(mPresContext);

  if (mPresContext) {
    // We hold a reference to the pres context, and it holds a weak link back
    // to us. To avoid the pres context having a dangling reference, set its 
    // pres shell to NULL
    mPresContext->SetShell(nullptr);

    // Clear the link handler (weak reference) as well
    mPresContext->SetLinkHandler(nullptr);
  }

  mHaveShutDown = true;
}

void
nsIPresShell::SetAuthorStyleDisabled(bool aStyleDisabled)
{
  if (aStyleDisabled != mStyleSet->GetAuthorStyleDisabled()) {
    mStyleSet->SetAuthorStyleDisabled(aStyleDisabled);
    ReconstructStyleData();
  }
}

bool
nsIPresShell::GetAuthorStyleDisabled() const
{
  return mStyleSet->GetAuthorStyleDisabled();
}

nsresult
PresShell::SetPreferenceStyleRules(bool aForceReflow)
{
  if (!mDocument) {
    return NS_ERROR_NULL_POINTER;
  }

  nsPIDOMWindow *window = mDocument->GetWindow();

  // If the document doesn't have a window there's no need to notify
  // its presshell about changes to preferences since the document is
  // in a state where it doesn't matter any more (see
  // DocumentViewerImpl::Close()).

  if (!window) {
    return NS_ERROR_NULL_POINTER;
  } 

  NS_PRECONDITION(mPresContext, "presContext cannot be null");
  if (mPresContext) {
    // first, make sure this is not a chrome shell 
    if (nsContentUtils::IsInChromeDocshell(mDocument)) {
      return NS_OK;
    }

#ifdef DEBUG_attinasi
    printf("Setting Preference Style Rules:\n");
#endif
    // if here, we need to create rules for the prefs
    // - this includes the background-color, the text-color,
    //   the link color, the visited link color and the link-underlining
    
    // first clear any exising rules
    nsresult result = ClearPreferenceStyleRules();
      
    // now the link rules (must come after the color rules, or links will not be correct color!)
    // XXX - when there is both an override and agent pref stylesheet this won't matter,
    //       as the color rules will be overrides and the links rules will be agent
    if (NS_SUCCEEDED(result)) {
      result = SetPrefLinkRules();
    }
    if (NS_SUCCEEDED(result)) {
      result = SetPrefFocusRules();
    }
    if (NS_SUCCEEDED(result)) {
      result = SetPrefNoScriptRule();
    }
    if (NS_SUCCEEDED(result)) {
      result = SetPrefNoFramesRule();
    }
#ifdef DEBUG_attinasi
    printf( "Preference Style Rules set: error=%ld\n", (long)result);
#endif

    // Note that this method never needs to force any calculation; the caller
    // will recalculate style if needed

    return result;
  }

  return NS_ERROR_NULL_POINTER;
}

nsresult PresShell::ClearPreferenceStyleRules(void)
{
  nsresult result = NS_OK;
  if (mPrefStyleSheet) {
    NS_ASSERTION(mStyleSet, "null styleset entirely unexpected!");
    if (mStyleSet) {
      // remove the sheet from the styleset: 
      // - note that we have to check for success by comparing the count before and after...
#ifdef DEBUG
      int32_t numBefore = mStyleSet->SheetCount(nsStyleSet::eUserSheet);
      NS_ASSERTION(numBefore > 0, "no user stylesheets in styleset, but we have one!");
#endif
      mStyleSet->RemoveStyleSheet(nsStyleSet::eUserSheet, mPrefStyleSheet);

#ifdef DEBUG_attinasi
      NS_ASSERTION((numBefore - 1) == mStyleSet->GetNumberOfUserStyleSheets(),
                   "Pref stylesheet was not removed");
      printf("PrefStyleSheet removed\n");
#endif
      // clear the sheet pointer: it is strictly historical now
      mPrefStyleSheet = nullptr;
    }
  }
  return result;
}

nsresult
PresShell::CreatePreferenceStyleSheet()
{
  NS_ASSERTION(!mPrefStyleSheet, "prefStyleSheet already exists");
  mPrefStyleSheet = new nsCSSStyleSheet(CORS_NONE);
  nsCOMPtr<nsIURI> uri;
  nsresult rv = NS_NewURI(getter_AddRefs(uri), "about:PreferenceStyleSheet", nullptr);
  if (NS_FAILED(rv)) {
    mPrefStyleSheet = nullptr;
    return rv;
  }
  NS_ASSERTION(uri, "null but no error");
  mPrefStyleSheet->SetURIs(uri, uri, uri);
  mPrefStyleSheet->SetComplete();
  uint32_t index;
  rv =
    mPrefStyleSheet->InsertRuleInternal(NS_LITERAL_STRING("@namespace svg url(http://www.w3.org/2000/svg);"),
                                        0, &index);
  if (NS_FAILED(rv)) {
    mPrefStyleSheet = nullptr;
    return rv;
  }
  rv =
    mPrefStyleSheet->InsertRuleInternal(NS_LITERAL_STRING("@namespace url(http://www.w3.org/1999/xhtml);"),
                                        0, &index);
  if (NS_FAILED(rv)) {
    mPrefStyleSheet = nullptr;
    return rv;
  }

  mStyleSet->AppendStyleSheet(nsStyleSet::eUserSheet, mPrefStyleSheet);
  return NS_OK;
}

// XXX We want these after the @namespace rules.  Does order matter
// for these rules, or can we call StyleRule::StyleRuleCount()
// and just "append"?
static uint32_t sInsertPrefSheetRulesAt = 2;

nsresult
PresShell::SetPrefNoScriptRule()
{
  nsresult rv = NS_OK;

  // also handle the case where print is done from print preview
  // see bug #342439 for more details
  nsIDocument* doc = mDocument;
  if (doc->IsStaticDocument()) {
    doc = doc->GetOriginalDocument();
  }

  bool scriptEnabled = doc->IsScriptEnabled();
  if (scriptEnabled) {
    if (!mPrefStyleSheet) {
      rv = CreatePreferenceStyleSheet();
      NS_ENSURE_SUCCESS(rv, rv);
    }

    uint32_t index = 0;
    mPrefStyleSheet->
      InsertRuleInternal(NS_LITERAL_STRING("noscript{display:none!important}"),
                         sInsertPrefSheetRulesAt, &index);
  }

  return rv;
}

nsresult PresShell::SetPrefNoFramesRule(void)
{
  NS_ASSERTION(mPresContext,"null prescontext not allowed");
  if (!mPresContext) {
    return NS_ERROR_FAILURE;
  }

  nsresult rv = NS_OK;
  
  if (!mPrefStyleSheet) {
    rv = CreatePreferenceStyleSheet();
    NS_ENSURE_SUCCESS(rv, rv);
  }
  
  NS_ASSERTION(mPrefStyleSheet, "prefstylesheet should not be null");
  
  bool allowSubframes = true;
  nsCOMPtr<nsISupports> container = mPresContext->GetContainer();     
  nsCOMPtr<nsIDocShell> docShell(do_QueryInterface(container));
  if (docShell) {
    docShell->GetAllowSubframes(&allowSubframes);
  }
  if (!allowSubframes) {
    uint32_t index = 0;
    rv = mPrefStyleSheet->
      InsertRuleInternal(NS_LITERAL_STRING("noframes{display:block}"),
                         sInsertPrefSheetRulesAt, &index);
    NS_ENSURE_SUCCESS(rv, rv);
    rv = mPrefStyleSheet->
      InsertRuleInternal(NS_LITERAL_STRING("frame, frameset, iframe {display:none!important}"),
                         sInsertPrefSheetRulesAt, &index);
  }
  return rv;
}
  
nsresult PresShell::SetPrefLinkRules(void)
{
  NS_ASSERTION(mPresContext,"null prescontext not allowed");
  if (!mPresContext) {
    return NS_ERROR_FAILURE;
  }

  nsresult rv = NS_OK;
  
  if (!mPrefStyleSheet) {
    rv = CreatePreferenceStyleSheet();
    NS_ENSURE_SUCCESS(rv, rv);
  }
  
  NS_ASSERTION(mPrefStyleSheet, "prefstylesheet should not be null");
  
  // support default link colors: 
  //   this means the link colors need to be overridable, 
  //   which they are if we put them in the agent stylesheet,
  //   though if using an override sheet this will cause authors grief still
  //   In the agent stylesheet, they are !important when we are ignoring document colors
  
  nscolor linkColor(mPresContext->DefaultLinkColor());
  nscolor activeColor(mPresContext->DefaultActiveLinkColor());
  nscolor visitedColor(mPresContext->DefaultVisitedLinkColor());
  
  NS_NAMED_LITERAL_STRING(ruleClose, "}");
  uint32_t index = 0;
  nsAutoString strColor;

  // insert a rule to color links: '*|*:link {color: #RRGGBB [!important];}'
  ColorToString(linkColor, strColor);
  rv = mPrefStyleSheet->
    InsertRuleInternal(NS_LITERAL_STRING("*|*:link{color:") +
                       strColor + ruleClose,
                       sInsertPrefSheetRulesAt, &index);
  NS_ENSURE_SUCCESS(rv, rv);

  // - visited links: '*|*:visited {color: #RRGGBB [!important];}'
  ColorToString(visitedColor, strColor);
  rv = mPrefStyleSheet->
    InsertRuleInternal(NS_LITERAL_STRING("*|*:visited{color:") +
                       strColor + ruleClose,
                       sInsertPrefSheetRulesAt, &index);
  NS_ENSURE_SUCCESS(rv, rv);

  // - active links: '*|*:-moz-any-link:active {color: #RRGGBB [!important];}'
  ColorToString(activeColor, strColor);
  rv = mPrefStyleSheet->
    InsertRuleInternal(NS_LITERAL_STRING("*|*:-moz-any-link:active{color:") +
                       strColor + ruleClose,
                       sInsertPrefSheetRulesAt, &index);
  NS_ENSURE_SUCCESS(rv, rv);

  bool underlineLinks =
    mPresContext->GetCachedBoolPref(kPresContext_UnderlineLinks);

  if (underlineLinks) {
    // create a rule to make underlining happen
    //  '*|*:-moz-any-link {text-decoration:[underline|none];}'
    // no need for important, we want these to be overridable
    // NOTE: these must go in the agent stylesheet or they cannot be
    //       overridden by authors
    rv = mPrefStyleSheet->
      InsertRuleInternal(NS_LITERAL_STRING("*|*:-moz-any-link:not(svg|a){text-decoration:underline}"),
                         sInsertPrefSheetRulesAt, &index);
  } else {
    rv = mPrefStyleSheet->
      InsertRuleInternal(NS_LITERAL_STRING("*|*:-moz-any-link{text-decoration:none}"),
                         sInsertPrefSheetRulesAt, &index);
  }

  return rv;          
}

nsresult PresShell::SetPrefFocusRules(void)
{
  NS_ASSERTION(mPresContext,"null prescontext not allowed");
  nsresult result = NS_OK;

  if (!mPresContext)
    result = NS_ERROR_FAILURE;

  if (NS_SUCCEEDED(result) && !mPrefStyleSheet)
    result = CreatePreferenceStyleSheet();

  if (NS_SUCCEEDED(result)) {
    NS_ASSERTION(mPrefStyleSheet, "prefstylesheet should not be null");

    if (mPresContext->GetUseFocusColors()) {
      nscolor focusBackground(mPresContext->FocusBackgroundColor());
      nscolor focusText(mPresContext->FocusTextColor());

      // insert a rule to make focus the preferred color
      uint32_t index = 0;
      nsAutoString strRule, strColor;

      ///////////////////////////////////////////////////////////////
      // - focus: '*:focus
      ColorToString(focusText,strColor);
      strRule.AppendLiteral("*:focus,*:focus>font {color: ");
      strRule.Append(strColor);
      strRule.AppendLiteral(" !important; background-color: ");
      ColorToString(focusBackground,strColor);
      strRule.Append(strColor);
      strRule.AppendLiteral(" !important; } ");
      // insert the rules
      result = mPrefStyleSheet->
        InsertRuleInternal(strRule, sInsertPrefSheetRulesAt, &index);
    }
    uint8_t focusRingWidth = mPresContext->FocusRingWidth();
    bool focusRingOnAnything = mPresContext->GetFocusRingOnAnything();
    uint8_t focusRingStyle = mPresContext->GetFocusRingStyle();

    if ((NS_SUCCEEDED(result) && focusRingWidth != 1 && focusRingWidth <= 4 ) || focusRingOnAnything) {
      uint32_t index = 0;
      nsAutoString strRule;
      if (!focusRingOnAnything)
        strRule.AppendLiteral("*|*:link:focus, *|*:visited");    // If we only want focus rings on the normal things like links
      strRule.AppendLiteral(":focus {outline: ");     // For example 3px dotted WindowText (maximum 4)
      strRule.AppendInt(focusRingWidth);
      if (focusRingStyle == 0) // solid
        strRule.AppendLiteral("px solid -moz-mac-focusring !important; -moz-outline-radius: 3px; outline-offset: 1px; } ");
      else // dotted
        strRule.AppendLiteral("px dotted WindowText !important; } ");
      // insert the rules
      result = mPrefStyleSheet->
        InsertRuleInternal(strRule, sInsertPrefSheetRulesAt, &index);
      NS_ENSURE_SUCCESS(result, result);
      if (focusRingWidth != 1) {
        // If the focus ring width is different from the default, fix buttons with rings
        strRule.AssignLiteral("button::-moz-focus-inner, input[type=\"reset\"]::-moz-focus-inner,");
        strRule.AppendLiteral("input[type=\"button\"]::-moz-focus-inner, ");
        strRule.AppendLiteral("input[type=\"submit\"]::-moz-focus-inner { padding: 1px 2px 1px 2px; border: ");
        strRule.AppendInt(focusRingWidth);
        if (focusRingStyle == 0) // solid
          strRule.AppendLiteral("px solid transparent !important; } ");
        else
          strRule.AppendLiteral("px dotted transparent !important; } ");
        result = mPrefStyleSheet->
          InsertRuleInternal(strRule, sInsertPrefSheetRulesAt, &index);
        NS_ENSURE_SUCCESS(result, result);
          
        strRule.AssignLiteral("button:focus::-moz-focus-inner, input[type=\"reset\"]:focus::-moz-focus-inner,");
        strRule.AppendLiteral("input[type=\"button\"]:focus::-moz-focus-inner, input[type=\"submit\"]:focus::-moz-focus-inner {");
        strRule.AppendLiteral("border-color: ButtonText !important; }");
        result = mPrefStyleSheet->
          InsertRuleInternal(strRule, sInsertPrefSheetRulesAt, &index);
      }
    }
  }
  return result;
}

void
PresShell::AddUserSheet(nsISupports* aSheet)
{
  // Make sure this does what DocumentViewerImpl::CreateStyleSet does wrt
  // ordering. We want this new sheet to come after all the existing stylesheet
  // service sheets, but before other user sheets; see nsIStyleSheetService.idl
  // for the ordering.  Just remove and readd all the nsStyleSheetService
  // sheets.
  nsCOMPtr<nsIStyleSheetService> dummy =
    do_GetService(NS_STYLESHEETSERVICE_CONTRACTID);

  mStyleSet->BeginUpdate();
  
  nsStyleSheetService *sheetService = nsStyleSheetService::gInstance;
  nsCOMArray<nsIStyleSheet> & userSheets = *sheetService->UserStyleSheets();
  int32_t i;
  // Iterate forwards when removing so the searches for RemoveStyleSheet are as
  // short as possible.
  for (i = 0; i < userSheets.Count(); ++i) {
    mStyleSet->RemoveStyleSheet(nsStyleSet::eUserSheet, userSheets[i]);
  }

  // Now iterate backwards, so that the order of userSheets will be the same as
  // the order of sheets from it in the style set.
  for (i = userSheets.Count() - 1; i >= 0; --i) {
    mStyleSet->PrependStyleSheet(nsStyleSet::eUserSheet, userSheets[i]);
  }

  mStyleSet->EndUpdate();

  ReconstructStyleData();
}

void
PresShell::AddAgentSheet(nsISupports* aSheet)
{
  // Make sure this does what DocumentViewerImpl::CreateStyleSet does
  // wrt ordering.
  nsCOMPtr<nsIStyleSheet> sheet = do_QueryInterface(aSheet);
  if (!sheet) {
    return;
  }

  mStyleSet->AppendStyleSheet(nsStyleSet::eAgentSheet, sheet);
  ReconstructStyleData();
}

void
PresShell::AddAuthorSheet(nsISupports* aSheet)
{
  nsCOMPtr<nsIStyleSheet> sheet = do_QueryInterface(aSheet);
  if (!sheet) {
    return;
  }

  // Document specific "additional" Author sheets should be stronger than the ones
  // added with the StyleSheetService.
  nsIStyleSheet* firstAuthorSheet = mDocument->FirstAdditionalAuthorSheet();
  if (firstAuthorSheet) {
    mStyleSet->InsertStyleSheetBefore(nsStyleSet::eDocSheet, sheet, firstAuthorSheet);
  } else {
    mStyleSet->AppendStyleSheet(nsStyleSet::eDocSheet, sheet);  
  }

  ReconstructStyleData();
}

void
PresShell::RemoveSheet(nsStyleSet::sheetType aType, nsISupports* aSheet)
{
  nsCOMPtr<nsIStyleSheet> sheet = do_QueryInterface(aSheet);
  if (!sheet) {
    return;
  }

  mStyleSet->RemoveStyleSheet(aType, sheet);
  ReconstructStyleData();
}

NS_IMETHODIMP
PresShell::SetDisplaySelection(int16_t aToggle)
{
  mSelection->SetDisplaySelection(aToggle);
  return NS_OK;
}

NS_IMETHODIMP
PresShell::GetDisplaySelection(int16_t *aToggle)
{
  *aToggle = mSelection->GetDisplaySelection();
  return NS_OK;
}

NS_IMETHODIMP
PresShell::GetSelection(SelectionType aType, nsISelection **aSelection)
{
  if (!aSelection || !mSelection)
    return NS_ERROR_NULL_POINTER;

  *aSelection = mSelection->GetSelection(aType);

  if (!(*aSelection))
    return NS_ERROR_INVALID_ARG;

  NS_ADDREF(*aSelection);

  return NS_OK;
}

nsISelection*
PresShell::GetCurrentSelection(SelectionType aType)
{
  if (!mSelection)
    return nullptr;

  return mSelection->GetSelection(aType);
}

NS_IMETHODIMP
PresShell::ScrollSelectionIntoView(SelectionType aType, SelectionRegion aRegion,
                                   int16_t aFlags)
{
  if (!mSelection)
    return NS_ERROR_NULL_POINTER;

  return mSelection->ScrollSelectionIntoView(aType, aRegion, aFlags);
}

NS_IMETHODIMP
PresShell::RepaintSelection(SelectionType aType)
{
  if (!mSelection)
    return NS_ERROR_NULL_POINTER;

  return mSelection->RepaintSelection(aType);
}

// Make shell be a document observer
void
PresShell::BeginObservingDocument()
{
  if (mDocument && !mIsDestroying) {
    mDocument->AddObserver(this);
    if (mIsDocumentGone) {
      NS_WARNING("Adding a presshell that was disconnected from the document "
                 "as a document observer?  Sounds wrong...");
      mIsDocumentGone = false;
    }
  }
}

// Make shell stop being a document observer
void
PresShell::EndObservingDocument()
{
  // XXXbz do we need to tell the frame constructor that the document
  // is gone, perhaps?  Except for printing it's NOT gone, sometimes.
  mIsDocumentGone = true;
  if (mDocument) {
    mDocument->RemoveObserver(this);
  }
}

#ifdef DEBUG_kipp
char* nsPresShell_ReflowStackPointerTop;
#endif

nsresult
PresShell::Initialize(nscoord aWidth, nscoord aHeight)
{
  if (mIsDestroying) {
    return NS_OK;
  }

  if (!mDocument) {
    // Nothing to do
    return NS_OK;
  }

  mozilla::TimeStamp timerStart = mozilla::TimeStamp::Now();

  NS_ASSERTION(!mDidInitialize, "Why are we being called?");

  nsCOMPtr<nsIPresShell> kungFuDeathGrip(this);
  mDidInitialize = true;

#ifdef DEBUG
  if (VERIFY_REFLOW_NOISY_RC & gVerifyReflowFlags) {
    if (mDocument) {
      nsIURI *uri = mDocument->GetDocumentURI();
      if (uri) {
        nsAutoCString url;
        uri->GetSpec(url);
        printf("*** PresShell::Initialize (this=%p, url='%s')\n", (void*)this, url.get());
      }
    }
  }
#endif

  if (mCaret)
    mCaret->EraseCaret();

  // XXX Do a full invalidate at the beginning so that invalidates along
  // the way don't have region accumulation issues?

  mPresContext->SetVisibleArea(nsRect(0, 0, aWidth, aHeight));

  // Get the root frame from the frame manager
  // XXXbz it would be nice to move this somewhere else... like frame manager
  // Init(), say.  But we need to make sure our views are all set up by the
  // time we do this!
  nsIFrame* rootFrame = mFrameConstructor->GetRootFrame();
  NS_ASSERTION(!rootFrame, "How did that happen, exactly?");
  if (!rootFrame) {
    nsAutoScriptBlocker scriptBlocker;
    mFrameConstructor->BeginUpdate();
    mFrameConstructor->ConstructRootFrame(&rootFrame);
    mFrameConstructor->SetRootFrame(rootFrame);
    mFrameConstructor->EndUpdate();
  }

  NS_ENSURE_STATE(!mHaveShutDown);

  if (!rootFrame) {
    return NS_ERROR_OUT_OF_MEMORY;
  }

  for (nsIFrame* f = rootFrame; f; f = nsLayoutUtils::GetCrossDocParentFrame(f)) {
    if (f->GetStateBits() & NS_FRAME_NO_COMPONENT_ALPHA) {
      f->InvalidateFrameSubtree();
      f->RemoveStateBits(NS_FRAME_NO_COMPONENT_ALPHA);
    }
  }

  Element *root = mDocument->GetRootElement();

  if (root) {
    {
      nsAutoCauseReflowNotifier reflowNotifier(this);
      mFrameConstructor->BeginUpdate();

      // Have the style sheet processor construct frame for the root
      // content object down
      mFrameConstructor->ContentInserted(nullptr, root, nullptr, false);
      VERIFY_STYLE_TREE;

      // Something in mFrameConstructor->ContentInserted may have caused
      // Destroy() to get called, bug 337586.
      NS_ENSURE_STATE(!mHaveShutDown);

      mFrameConstructor->EndUpdate();
    }

    // nsAutoScriptBlocker going out of scope may have killed us too
    NS_ENSURE_STATE(!mHaveShutDown);

    // Run the XBL binding constructors for any new frames we've constructed
    mDocument->BindingManager()->ProcessAttachedQueue();

    // Constructors may have killed us too
    NS_ENSURE_STATE(!mHaveShutDown);

    // Now flush out pending restyles before we actually reflow, in
    // case XBL constructors changed styles somewhere.
    {
      nsAutoScriptBlocker scriptBlocker;
      mFrameConstructor->CreateNeededFrames();
      mFrameConstructor->ProcessPendingRestyles();
    }

    // And that might have run _more_ XBL constructors
    NS_ENSURE_STATE(!mHaveShutDown);
  }

  NS_ASSERTION(rootFrame, "How did that happen?");

  // Note: when the frame was created above it had the NS_FRAME_IS_DIRTY bit
  // set, but XBL processing could have caused a reflow which clears it.
  if (MOZ_LIKELY(rootFrame->GetStateBits() & NS_FRAME_IS_DIRTY)) {
    // Unset the DIRTY bits so that FrameNeedsReflow() will work right.
    rootFrame->RemoveStateBits(NS_FRAME_IS_DIRTY |
                               NS_FRAME_HAS_DIRTY_CHILDREN);
    NS_ASSERTION(!mDirtyRoots.Contains(rootFrame),
                 "Why is the root in mDirtyRoots already?");
    FrameNeedsReflow(rootFrame, eResize, NS_FRAME_IS_DIRTY);
    NS_ASSERTION(mDirtyRoots.Contains(rootFrame),
                 "Should be in mDirtyRoots now");
    NS_ASSERTION(mReflowScheduled, "Why no reflow scheduled?");
  }

  // Restore our root scroll position now if we're getting here after EndLoad
  // got called, since this is our one chance to do it.  Note that we need not
  // have reflowed for this to work; when the scrollframe is finally reflowed
  // it'll pick up the position we store in it here.
  if (!mDocumentLoading) {
    RestoreRootScrollPosition();
  }

  // For printing, we just immediately unsuppress.
  if (!mPresContext->IsPaginated()) {
    // Kick off a one-shot timer based off our pref value.  When this timer
    // fires, if painting is still locked down, then we will go ahead and
    // trigger a full invalidate and allow painting to proceed normally.
    mPaintingSuppressed = true;
    // Don't suppress painting if the document isn't loading.
    nsIDocument::ReadyState readyState = mDocument->GetReadyStateEnum();
    if (readyState != nsIDocument::READYSTATE_COMPLETE) {
      mPaintSuppressionTimer = do_CreateInstance("@mozilla.org/timer;1");
    }
    if (!mPaintSuppressionTimer) {
      mPaintingSuppressed = false;
    } else {
      // Initialize the timer.

      // Default to PAINTLOCK_EVENT_DELAY if we can't get the pref value.
      int32_t delay =
        Preferences::GetInt("nglayout.initialpaint.delay",
                            PAINTLOCK_EVENT_DELAY);

      mPaintSuppressionTimer->InitWithFuncCallback(sPaintSuppressionCallback,
                                                   this, delay, 
                                                   nsITimer::TYPE_ONE_SHOT);
    }
  }

  if (root && root->IsXUL()) {
    mozilla::Telemetry::AccumulateTimeDelta(Telemetry::XUL_INITIAL_FRAME_CONSTRUCTION,
                                            timerStart);
  }

  return NS_OK; //XXX this needs to be real. MMP
}

void
PresShell::sPaintSuppressionCallback(nsITimer *aTimer, void* aPresShell)
{
  nsRefPtr<PresShell> self = static_cast<PresShell*>(aPresShell);
  if (self)
    self->UnsuppressPainting();
}

void
PresShell::AsyncResizeEventCallback(nsITimer* aTimer, void* aPresShell)
{
  static_cast<PresShell*>(aPresShell)->FireResizeEvent();
}

nsresult
PresShell::ResizeReflowOverride(nscoord aWidth, nscoord aHeight)
{
  mViewportOverridden = true;
  return ResizeReflowIgnoreOverride(aWidth, aHeight);
}

nsresult
PresShell::ResizeReflow(nscoord aWidth, nscoord aHeight)
{
  if (mViewportOverridden) {
    // The viewport has been overridden, and this reflow request
    // didn't ask to ignore the override.  Pretend it didn't happen.
    return NS_OK;
  }
  return ResizeReflowIgnoreOverride(aWidth, aHeight);
}

nsresult
PresShell::ResizeReflowIgnoreOverride(nscoord aWidth, nscoord aHeight)
{
  NS_PRECONDITION(!mIsReflowing, "Shouldn't be in reflow here!");
  NS_PRECONDITION(aWidth != NS_UNCONSTRAINEDSIZE,
                  "shouldn't use unconstrained widths anymore");
  
  // If we don't have a root frame yet, that means we haven't had our initial
  // reflow... If that's the case, and aWidth or aHeight is unconstrained,
  // ignore them altogether.
  nsIFrame* rootFrame = mFrameConstructor->GetRootFrame();

  if (!rootFrame && aHeight == NS_UNCONSTRAINEDSIZE) {
    // We can't do the work needed for SizeToContent without a root
    // frame, and we want to return before setting the visible area.
    return NS_ERROR_NOT_AVAILABLE;
  }

  nsCOMPtr<nsIViewManager> viewManagerDeathGrip = mViewManager;
  // Take this ref after viewManager so it'll make sure to go away first
  nsCOMPtr<nsIPresShell> kungFuDeathGrip(this);

  if (!mIsDestroying && !mResizeEvent.IsPending() &&
      !mAsyncResizeTimerIsActive) {
    FireBeforeResizeEvent();
  }

  mPresContext->SetVisibleArea(nsRect(0, 0, aWidth, aHeight));

  // There isn't anything useful we can do if the initial reflow hasn't happened
  rootFrame = mFrameConstructor->GetRootFrame();
  if (!rootFrame)
    return NS_OK;

  if (!GetPresContext()->SupressingResizeReflow())
  {
    // Have to make sure that the content notifications are flushed before we
    // start messing with the frame model; otherwise we can get content doubling.
    mDocument->FlushPendingNotifications(Flush_ContentAndNotify);

    // Make sure style is up to date
    {
      nsAutoScriptBlocker scriptBlocker;
      mFrameConstructor->CreateNeededFrames();
      mFrameConstructor->ProcessPendingRestyles();
    }

    rootFrame = mFrameConstructor->GetRootFrame();
    if (!mIsDestroying && rootFrame) {
      // XXX Do a full invalidate at the beginning so that invalidates along
      // the way don't have region accumulation issues?

      {
        nsAutoCauseReflowNotifier crNotifier(this);
        WillDoReflow();

        // Kick off a top-down reflow
        AUTO_LAYOUT_PHASE_ENTRY_POINT(GetPresContext(), Reflow);
        nsIViewManager::AutoDisableRefresh refreshBlocker(mViewManager);

        mDirtyRoots.RemoveElement(rootFrame);
        DoReflow(rootFrame, true);
      }

      DidDoReflow(true);
    }
  }

  rootFrame = mFrameConstructor->GetRootFrame();
  if (aHeight == NS_UNCONSTRAINEDSIZE && rootFrame) {
    mPresContext->SetVisibleArea(
      nsRect(0, 0, aWidth, rootFrame->GetRect().height));
  }

  if (!mIsDestroying && !mResizeEvent.IsPending() &&
      !mAsyncResizeTimerIsActive) {
    if (mInResize) {
      if (!mAsyncResizeEventTimer) {
        mAsyncResizeEventTimer = do_CreateInstance("@mozilla.org/timer;1");
      }
      if (mAsyncResizeEventTimer) {
        mAsyncResizeTimerIsActive = true;
        mAsyncResizeEventTimer->InitWithFuncCallback(AsyncResizeEventCallback,
                                                     this, 15,
                                                     nsITimer::TYPE_ONE_SHOT);
      }
    } else {
      nsRefPtr<nsRunnableMethod<PresShell> > resizeEvent =
        NS_NewRunnableMethod(this, &PresShell::FireResizeEvent);
      if (NS_SUCCEEDED(NS_DispatchToCurrentThread(resizeEvent))) {
        mResizeEvent = resizeEvent;
        mDocument->SetNeedStyleFlush();
      }
    }
  }

  return NS_OK; //XXX this needs to be real. MMP
}

void
PresShell::FireBeforeResizeEvent()
{
  if (mIsDocumentGone)
    return;

  // Send beforeresize event from here.
  nsEvent event(true, NS_BEFORERESIZE_EVENT);

  nsPIDOMWindow *window = mDocument->GetWindow();
  if (window) {
    nsCOMPtr<nsIPresShell> kungFuDeathGrip(this);
    nsEventDispatcher::Dispatch(window, mPresContext, &event);
  }
}

void
PresShell::FireResizeEvent()
{
  if (mAsyncResizeTimerIsActive) {
    mAsyncResizeTimerIsActive = false;
    mAsyncResizeEventTimer->Cancel();
  }
  mResizeEvent.Revoke();

  if (mIsDocumentGone)
    return;

  //Send resize event from here.
  nsEvent event(true, NS_RESIZE_EVENT);
  nsEventStatus status = nsEventStatus_eIgnore;

  nsPIDOMWindow *window = mDocument->GetWindow();
  if (window) {
    nsCOMPtr<nsIPresShell> kungFuDeathGrip(this);
    mInResize = true;
    nsEventDispatcher::Dispatch(window, mPresContext, &event, nullptr, &status);
    mInResize = false;
  }
}

void
PresShell::SetIgnoreFrameDestruction(bool aIgnore)
{
  if (mDocument) {
    // We need to tell the ImageLoader to drop all its references to frames
    // because they're about to go away and it won't get notifications of that.
    mDocument->StyleImageLoader()->ClearAll();
  }
  mIgnoreFrameDestruction = aIgnore;
}

void
PresShell::NotifyDestroyingFrame(nsIFrame* aFrame)
{
  if (!mIgnoreFrameDestruction) {
    mDocument->StyleImageLoader()->DropRequestsForFrame(aFrame);

    mFrameConstructor->NotifyDestroyingFrame(aFrame);

    for (int32_t idx = mDirtyRoots.Length(); idx; ) {
      --idx;
      if (mDirtyRoots[idx] == aFrame) {
        mDirtyRoots.RemoveElementAt(idx);
      }
    }

    // Remove frame properties
    mPresContext->NotifyDestroyingFrame(aFrame);

    if (aFrame == mCurrentEventFrame) {
      mCurrentEventContent = aFrame->GetContent();
      mCurrentEventFrame = nullptr;
    }

  #ifdef DEBUG
    if (aFrame == mDrawEventTargetFrame) {
      mDrawEventTargetFrame = nullptr;
    }
  #endif

    for (unsigned int i=0; i < mCurrentEventFrameStack.Length(); i++) {
      if (aFrame == mCurrentEventFrameStack.ElementAt(i)) {
        //One of our stack frames was deleted.  Get its content so that when we
        //pop it we can still get its new frame from its content
        nsIContent *currentEventContent = aFrame->GetContent();
        mCurrentEventContentStack.ReplaceObjectAt(currentEventContent, i);
        mCurrentEventFrameStack[i] = nullptr;
      }
    }
  
    mFramesToDirty.RemoveEntry(aFrame);
  } else {
    // We must delete this property in situ so that its destructor removes the
    // frame from FrameLayerBuilder::DisplayItemData::mFrameList -- otherwise
    // the DisplayItemData destructor will use the destroyed frame when it
    // tries to remove it from the (array) value of this property.
    mPresContext->PropertyTable()->
      Delete(aFrame, FrameLayerBuilder::LayerManagerDataProperty());
  }
}

already_AddRefed<nsCaret> PresShell::GetCaret() const
{
  nsCaret* caret = mCaret;
  NS_IF_ADDREF(caret);
  return caret;
}

void PresShell::MaybeInvalidateCaretPosition()
{
  if (mCaret) {
    mCaret->InvalidateOutsideCaret();
  }
}

void PresShell::SetCaret(nsCaret *aNewCaret)
{
  mCaret = aNewCaret;
}

void PresShell::RestoreCaret()
{
  mCaret = mOriginalCaret;
}

NS_IMETHODIMP PresShell::SetCaretEnabled(bool aInEnable)
{
  bool oldEnabled = mCaretEnabled;

  mCaretEnabled = aInEnable;

  if (mCaret && (mCaretEnabled != oldEnabled))
  {
/*  Don't change the caret's selection here! This was an evil side-effect of SetCaretEnabled()
    nsCOMPtr<nsIDOMSelection> domSel;
    if (NS_SUCCEEDED(GetSelection(nsISelectionController::SELECTION_NORMAL, getter_AddRefs(domSel))) && domSel)
      mCaret->SetCaretDOMSelection(domSel);
*/
    mCaret->SetCaretVisible(mCaretEnabled);
  }

  return NS_OK;
}

NS_IMETHODIMP PresShell::SetCaretReadOnly(bool aReadOnly)
{
  if (mCaret)
    mCaret->SetCaretReadOnly(aReadOnly);
  return NS_OK;
}

NS_IMETHODIMP PresShell::GetCaretEnabled(bool *aOutEnabled)
{
  NS_ENSURE_ARG_POINTER(aOutEnabled);
  *aOutEnabled = mCaretEnabled;
  return NS_OK;
}

NS_IMETHODIMP PresShell::SetCaretVisibilityDuringSelection(bool aVisibility)
{
  if (mCaret)
    mCaret->SetVisibilityDuringSelection(aVisibility);
  return NS_OK;
}

NS_IMETHODIMP PresShell::GetCaretVisible(bool *aOutIsVisible)
{
  *aOutIsVisible = false;
  if (mCaret) {
    nsresult rv = mCaret->GetCaretVisible(aOutIsVisible);
    NS_ENSURE_SUCCESS(rv,rv);
  }
  return NS_OK;
}

NS_IMETHODIMP PresShell::SetSelectionFlags(int16_t aInEnable)
{
  mSelectionFlags = aInEnable;
  return NS_OK;
}

NS_IMETHODIMP PresShell::GetSelectionFlags(int16_t *aOutEnable)
{
  if (!aOutEnable)
    return NS_ERROR_INVALID_ARG;
  *aOutEnable = mSelectionFlags;
  return NS_OK;
}

//implementation of nsISelectionController

NS_IMETHODIMP 
PresShell::CharacterMove(bool aForward, bool aExtend)
{
  return mSelection->CharacterMove(aForward, aExtend);  
}

NS_IMETHODIMP
PresShell::CharacterExtendForDelete()
{
  return mSelection->CharacterExtendForDelete();
}

NS_IMETHODIMP
PresShell::CharacterExtendForBackspace()
{
  return mSelection->CharacterExtendForBackspace();
}

NS_IMETHODIMP 
PresShell::WordMove(bool aForward, bool aExtend)
{
  nsresult result = mSelection->WordMove(aForward, aExtend);
// if we can't go down/up any more we must then move caret completely to
// end/beginning respectively.
  if (NS_FAILED(result))
    result = CompleteMove(aForward, aExtend);
  return result;
}

NS_IMETHODIMP 
PresShell::WordExtendForDelete(bool aForward)
{
  return mSelection->WordExtendForDelete(aForward);  
}

NS_IMETHODIMP 
PresShell::LineMove(bool aForward, bool aExtend)
{
  nsresult result = mSelection->LineMove(aForward, aExtend);  
// if we can't go down/up any more we must then move caret completely to 
// end/beginning respectively.
  if (NS_FAILED(result)) 
    result = CompleteMove(aForward,aExtend);
  return result;
}

NS_IMETHODIMP 
PresShell::IntraLineMove(bool aForward, bool aExtend)
{
  return mSelection->IntraLineMove(aForward, aExtend);  
}



NS_IMETHODIMP 
PresShell::PageMove(bool aForward, bool aExtend)
{
  nsIScrollableFrame *scrollableFrame =
    GetFrameToScrollAsScrollable(nsIPresShell::eVertical);
  if (!scrollableFrame)
    return NS_OK;

  mSelection->CommonPageMove(aForward, aExtend, scrollableFrame);
  // After ScrollSelectionIntoView(), the pending notifications might be
  // flushed and PresShell/PresContext/Frames may be dead. See bug 418470.
  return ScrollSelectionIntoView(nsISelectionController::SELECTION_NORMAL,
                                 nsISelectionController::SELECTION_FOCUS_REGION,
                                 nsISelectionController::SCROLL_SYNCHRONOUS);
}



NS_IMETHODIMP 
PresShell::ScrollPage(bool aForward)
{
  nsIScrollableFrame* scrollFrame =
    GetFrameToScrollAsScrollable(nsIPresShell::eVertical);
  if (scrollFrame) {
    scrollFrame->ScrollBy(nsIntPoint(0, aForward ? 1 : -1),
                          nsIScrollableFrame::PAGES,
                          nsIScrollableFrame::SMOOTH);
  }
  return NS_OK;
}

NS_IMETHODIMP
PresShell::ScrollLine(bool aForward)
{
  nsIScrollableFrame* scrollFrame =
    GetFrameToScrollAsScrollable(nsIPresShell::eVertical);
  if (scrollFrame) {
    int32_t lineCount = Preferences::GetInt("toolkit.scrollbox.verticalScrollDistance",
                                            NS_DEFAULT_VERTICAL_SCROLL_DISTANCE);
    scrollFrame->ScrollBy(nsIntPoint(0, aForward ? lineCount : -lineCount),
                          nsIScrollableFrame::LINES,
                          nsIScrollableFrame::SMOOTH);
  }
  return NS_OK;
}

NS_IMETHODIMP
PresShell::ScrollCharacter(bool aRight)
{
  nsIScrollableFrame* scrollFrame =
    GetFrameToScrollAsScrollable(nsIPresShell::eHorizontal);
  if (scrollFrame) {
    int32_t h = Preferences::GetInt("toolkit.scrollbox.horizontalScrollDistance",
                                    NS_DEFAULT_HORIZONTAL_SCROLL_DISTANCE);
    scrollFrame->ScrollBy(nsIntPoint(aRight ? h : -h, 0),
                          nsIScrollableFrame::LINES,
                          nsIScrollableFrame::SMOOTH);
  }
  return NS_OK;
}

NS_IMETHODIMP
PresShell::CompleteScroll(bool aForward)
{
  nsIScrollableFrame* scrollFrame =
    GetFrameToScrollAsScrollable(nsIPresShell::eVertical);
  if (scrollFrame) {
    scrollFrame->ScrollBy(nsIntPoint(0, aForward ? 1 : -1),
                          nsIScrollableFrame::WHOLE,
                          nsIScrollableFrame::INSTANT);
  }
  return NS_OK;
}

NS_IMETHODIMP
PresShell::CompleteMove(bool aForward, bool aExtend)
{
  // Beware! This may flush notifications via synchronous
  // ScrollSelectionIntoView.
  nsIContent* limiter = mSelection->GetAncestorLimiter();
  nsIFrame* frame = limiter ? limiter->GetPrimaryFrame()
                            : FrameConstructor()->GetRootElementFrame();
  if (!frame)
    return NS_ERROR_FAILURE;
  nsIFrame::CaretPosition pos =
    frame->GetExtremeCaretPosition(!aForward);
  mSelection->HandleClick(pos.mResultContent, pos.mContentOffset,
                          pos.mContentOffset, aExtend, false, aForward);
  if (limiter) {
    // HandleClick resets ancestorLimiter, so set it again.
    mSelection->SetAncestorLimiter(limiter);
  }
    
  // After ScrollSelectionIntoView(), the pending notifications might be
  // flushed and PresShell/PresContext/Frames may be dead. See bug 418470.
  return ScrollSelectionIntoView(nsISelectionController::SELECTION_NORMAL, 
                                 nsISelectionController::SELECTION_FOCUS_REGION,
                                 nsISelectionController::SCROLL_SYNCHRONOUS);
}

NS_IMETHODIMP 
PresShell::SelectAll()
{
  return mSelection->SelectAll();
}

static void
DoCheckVisibility(nsPresContext* aPresContext,
                  nsIContent* aNode,
                  int16_t aStartOffset,
                  int16_t aEndOffset,
                  bool* aRetval)
{
  nsIFrame* frame = aNode->GetPrimaryFrame();
  if (!frame) {
    // No frame to look at so it must not be visible.
    return;
  }

  // Start process now to go through all frames to find startOffset. Then check
  // chars after that to see if anything until EndOffset is visible.
  bool finished = false;
  frame->CheckVisibility(aPresContext, aStartOffset, aEndOffset, true,
                         &finished, aRetval);
  // Don't worry about other return value.
}

NS_IMETHODIMP
PresShell::CheckVisibility(nsIDOMNode *node, int16_t startOffset, int16_t EndOffset, bool *_retval)
{
  if (!node || startOffset>EndOffset || !_retval || startOffset<0 || EndOffset<0)
    return NS_ERROR_INVALID_ARG;
  *_retval = false; //initialize return parameter
  nsCOMPtr<nsIContent> content(do_QueryInterface(node));
  if (!content)
    return NS_ERROR_FAILURE;

  DoCheckVisibility(mPresContext, content, startOffset, EndOffset, _retval);
  return NS_OK;
}

nsresult
PresShell::CheckVisibilityContent(nsIContent* aNode, int16_t aStartOffset,
                                  int16_t aEndOffset, bool* aRetval)
{
  if (!aNode || aStartOffset > aEndOffset || !aRetval ||
      aStartOffset < 0 || aEndOffset < 0) {
    return NS_ERROR_INVALID_ARG;
  }

  *aRetval = false;
  DoCheckVisibility(mPresContext, aNode, aStartOffset, aEndOffset, aRetval);
  return NS_OK;
}

//end implementations nsISelectionController


void
PresShell::StyleChangeReflow()
{
  nsIFrame* rootFrame = mFrameConstructor->GetRootFrame();
  // At the moment at least, we don't have a root frame before the initial
  // reflow; it's safe to just ignore the request in that case
  if (!rootFrame)
    return;

  FrameNeedsReflow(rootFrame, eStyleChange, NS_FRAME_IS_DIRTY);
}

nsIFrame*
nsIPresShell::GetRootFrameExternal() const
{
  return mFrameConstructor->GetRootFrame();
}

nsIFrame*
nsIPresShell::GetRootScrollFrame() const
{
  nsIFrame* rootFrame = mFrameConstructor->GetRootFrame();
  // Ensure root frame is a viewport frame
  if (!rootFrame || nsGkAtoms::viewportFrame != rootFrame->GetType())
    return nullptr;
  nsIFrame* theFrame = rootFrame->GetFirstPrincipalChild();
  if (!theFrame || nsGkAtoms::scrollFrame != theFrame->GetType())
    return nullptr;
  return theFrame;
}

nsIScrollableFrame*
nsIPresShell::GetRootScrollFrameAsScrollable() const
{
  nsIFrame* frame = GetRootScrollFrame();
  if (!frame)
    return nullptr;
  nsIScrollableFrame* scrollableFrame = do_QueryFrame(frame);
  NS_ASSERTION(scrollableFrame,
               "All scroll frames must implement nsIScrollableFrame");
  return scrollableFrame;
}

nsIScrollableFrame*
nsIPresShell::GetRootScrollFrameAsScrollableExternal() const
{
  return GetRootScrollFrameAsScrollable();
}

nsIPageSequenceFrame*
PresShell::GetPageSequenceFrame() const
{
  nsIFrame* frame = mFrameConstructor->GetPageSequenceFrame();
  return do_QueryFrame(frame);
}

void
PresShell::BeginUpdate(nsIDocument *aDocument, nsUpdateType aUpdateType)
{
#ifdef DEBUG
  mUpdateCount++;
#endif
  mFrameConstructor->BeginUpdate();

  if (aUpdateType & UPDATE_STYLE)
    mStyleSet->BeginUpdate();
}

void
PresShell::EndUpdate(nsIDocument *aDocument, nsUpdateType aUpdateType)
{
#ifdef DEBUG
  NS_PRECONDITION(0 != mUpdateCount, "too many EndUpdate's");
  --mUpdateCount;
#endif

  if (aUpdateType & UPDATE_STYLE) {
    mStyleSet->EndUpdate();
    if (mStylesHaveChanged)
      ReconstructStyleData();
  }

  mFrameConstructor->EndUpdate();
}

void
PresShell::RestoreRootScrollPosition()
{
  // Restore frame state for the root scroll frame
  nsCOMPtr<nsILayoutHistoryState> historyState =
    mDocument->GetLayoutHistoryState();
  // Make sure we don't reenter reflow via the sync paint that happens while
  // we're scrolling to our restored position.  Entering reflow for the
  // scrollable frame will cause it to reenter ScrollToRestoredPosition(), and
  // it'll get all confused.
  nsAutoScriptBlocker scriptBlocker;
  ++mChangeNestCount;

  if (historyState) {
    nsIFrame* scrollFrame = GetRootScrollFrame();
    if (scrollFrame) {
      nsIScrollableFrame* scrollableFrame = do_QueryFrame(scrollFrame);
      if (scrollableFrame) {
        mFrameConstructor->RestoreFrameStateFor(scrollFrame, historyState,
                                                nsIStatefulFrame::eDocumentScrollState);
        scrollableFrame->ScrollToRestoredPosition();
      }
    }
  }

  --mChangeNestCount;
}

void
PresShell::BeginLoad(nsIDocument *aDocument)
{  
  mDocumentLoading = true;
}

void
PresShell::EndLoad(nsIDocument *aDocument)
{
  NS_PRECONDITION(aDocument == mDocument, "Wrong document");
  
  RestoreRootScrollPosition();
  
  mDocumentLoading = false;
}

#ifdef DEBUG
void
PresShell::VerifyHasDirtyRootAncestor(nsIFrame* aFrame)
{
  // XXXbz due to bug 372769, can't actually assert anything here...
  return;
  
  // XXXbz shouldn't need this part; remove it once FrameNeedsReflow
  // handles the root frame correctly.
  if (!aFrame->GetParent()) {
    return;
  }
        
  // Make sure that there is a reflow root ancestor of |aFrame| that's
  // in mDirtyRoots already.
  while (aFrame && (aFrame->GetStateBits() & NS_FRAME_HAS_DIRTY_CHILDREN)) {
    if (((aFrame->GetStateBits() & NS_FRAME_REFLOW_ROOT) ||
         !aFrame->GetParent()) &&
        mDirtyRoots.Contains(aFrame)) {
      return;
    }

    aFrame = aFrame->GetParent();
  }
  NS_NOTREACHED("Frame has dirty bits set but isn't scheduled to be "
                "reflowed?");
}
#endif

void
PresShell::FrameNeedsReflow(nsIFrame *aFrame, IntrinsicDirty aIntrinsicDirty,
                            nsFrameState aBitToAdd)
{
  NS_PRECONDITION(aBitToAdd == NS_FRAME_IS_DIRTY ||
                  aBitToAdd == NS_FRAME_HAS_DIRTY_CHILDREN,
                  "Unexpected bits being added");
  NS_PRECONDITION(aIntrinsicDirty != eStyleChange ||
                  aBitToAdd == NS_FRAME_IS_DIRTY,
                  "bits don't correspond to style change reason");

  NS_ASSERTION(!mIsReflowing, "can't mark frame dirty during reflow");

  // If we've not yet done the initial reflow, then don't bother
  // enqueuing a reflow command yet.
  if (! mDidInitialize)
    return;

  // If we're already destroying, don't bother with this either.
  if (mIsDestroying)
    return;

#ifdef DEBUG
  //printf("gShellCounter: %d\n", gShellCounter++);
  if (mInVerifyReflow)
    return;

  if (VERIFY_REFLOW_NOISY_RC & gVerifyReflowFlags) {
    printf("\nPresShell@%p: frame %p needs reflow\n", (void*)this, (void*)aFrame);
    if (VERIFY_REFLOW_REALLY_NOISY_RC & gVerifyReflowFlags) {
      printf("Current content model:\n");
      Element *rootElement = mDocument->GetRootElement();
      if (rootElement) {
        rootElement->List(stdout, 0);
      }
    }
  }  
#endif

  nsAutoTArray<nsIFrame*, 4> subtrees;
  subtrees.AppendElement(aFrame);

  do {
    nsIFrame *subtreeRoot = subtrees.ElementAt(subtrees.Length() - 1);
    subtrees.RemoveElementAt(subtrees.Length() - 1);

    // Grab |wasDirty| now so we can go ahead and update the bits on
    // subtreeRoot.
    bool wasDirty = NS_SUBTREE_DIRTY(subtreeRoot);
    subtreeRoot->AddStateBits(aBitToAdd);

    // Now if subtreeRoot is a reflow root we can cut off this reflow at it if
    // the bit being added is NS_FRAME_HAS_DIRTY_CHILDREN.
    bool targetFrameDirty = (aBitToAdd == NS_FRAME_IS_DIRTY);

#define FRAME_IS_REFLOW_ROOT(_f)                   \
  ((_f->GetStateBits() & NS_FRAME_REFLOW_ROOT) &&  \
   (_f != subtreeRoot || !targetFrameDirty))


    // Mark the intrinsic widths as dirty on the frame, all of its ancestors,
    // and all of its descendants, if needed:

    if (aIntrinsicDirty != eResize) {
      // Mark argument and all ancestors dirty. (Unless we hit a reflow
      // root that should contain the reflow.  That root could be
      // subtreeRoot itself if it's not dirty, or it could be some
      // ancestor of subtreeRoot.)
      for (nsIFrame *a = subtreeRoot;
           a && !FRAME_IS_REFLOW_ROOT(a);
           a = a->GetParent())
        a->MarkIntrinsicWidthsDirty();
    }

    if (aIntrinsicDirty == eStyleChange) {
      // Mark all descendants dirty (using an nsTArray stack rather than
      // recursion).
      // Note that nsHTMLReflowState::InitResizeFlags has some similar
      // code; see comments there for how and why it differs.
      nsAutoTArray<nsIFrame*, 32> stack;
      stack.AppendElement(subtreeRoot);

      do {
        nsIFrame *f = stack.ElementAt(stack.Length() - 1);
        stack.RemoveElementAt(stack.Length() - 1);

        if (f->GetType() == nsGkAtoms::placeholderFrame) {
          nsIFrame *oof = nsPlaceholderFrame::GetRealFrameForPlaceholder(f);
          if (!nsLayoutUtils::IsProperAncestorFrame(subtreeRoot, oof)) {
            // We have another distinct subtree we need to mark.
            subtrees.AppendElement(oof);
          }
        }

        nsIFrame::ChildListIterator lists(f);
        for (; !lists.IsDone(); lists.Next()) {
          nsFrameList::Enumerator childFrames(lists.CurrentList());
          for (; !childFrames.AtEnd(); childFrames.Next()) {
            nsIFrame* kid = childFrames.get();
            kid->MarkIntrinsicWidthsDirty();
            stack.AppendElement(kid);
          }
        }
      } while (stack.Length() != 0);
    }

    // Set NS_FRAME_HAS_DIRTY_CHILDREN bits (via nsIFrame::ChildIsDirty)
    // up the tree until we reach either a frame that's already dirty or
    // a reflow root.
    nsIFrame *f = subtreeRoot;
    for (;;) {
      if (FRAME_IS_REFLOW_ROOT(f) || !f->GetParent()) {
        // we've hit a reflow root or the root frame
        if (!wasDirty) {
          mDirtyRoots.AppendElement(f);
          mDocument->SetNeedLayoutFlush();
        }
#ifdef DEBUG
        else {
          VerifyHasDirtyRootAncestor(f);
        }
#endif
        
        break;
      }

      nsIFrame *child = f;
      f = f->GetParent();
      wasDirty = NS_SUBTREE_DIRTY(f);
      f->ChildIsDirty(child);
      NS_ASSERTION(f->GetStateBits() & NS_FRAME_HAS_DIRTY_CHILDREN,
                   "ChildIsDirty didn't do its job");
      if (wasDirty) {
        // This frame was already marked dirty.
#ifdef DEBUG
        VerifyHasDirtyRootAncestor(f);
#endif
        break;
      }
    }
  } while (subtrees.Length() != 0);

  MaybeScheduleReflow();
}

void
PresShell::FrameNeedsToContinueReflow(nsIFrame *aFrame)
{
  NS_ASSERTION(mIsReflowing, "Must be in reflow when marking path dirty.");  
  NS_PRECONDITION(mCurrentReflowRoot, "Must have a current reflow root here");
  NS_ASSERTION(aFrame == mCurrentReflowRoot ||
               nsLayoutUtils::IsProperAncestorFrame(mCurrentReflowRoot, aFrame),
               "Frame passed in is not the descendant of mCurrentReflowRoot");
  NS_ASSERTION(aFrame->GetStateBits() & NS_FRAME_IN_REFLOW,
               "Frame passed in not in reflow?");

  mFramesToDirty.PutEntry(aFrame);
}

nsIScrollableFrame*
nsIPresShell::GetFrameToScrollAsScrollable(
                nsIPresShell::ScrollDirection aDirection)
{
  nsIScrollableFrame* scrollFrame = nullptr;

  nsCOMPtr<nsIContent> focusedContent;
  nsIFocusManager* fm = nsFocusManager::GetFocusManager();
  if (fm && mDocument) {
    nsCOMPtr<nsIDOMWindow> window = do_QueryInterface(mDocument->GetWindow());

    nsCOMPtr<nsIDOMElement> focusedElement;
    fm->GetFocusedElementForWindow(window, false, nullptr, getter_AddRefs(focusedElement));
    focusedContent = do_QueryInterface(focusedElement);
  }
  if (!focusedContent && mSelection) {
    nsISelection* domSelection = mSelection->
      GetSelection(nsISelectionController::SELECTION_NORMAL);
    if (domSelection) {
      nsCOMPtr<nsIDOMNode> focusedNode;
      domSelection->GetFocusNode(getter_AddRefs(focusedNode));
      focusedContent = do_QueryInterface(focusedNode);
    }
  }
  if (focusedContent) {
    nsIFrame* startFrame = focusedContent->GetPrimaryFrame();
    if (startFrame) {
      scrollFrame = startFrame->GetScrollTargetFrame();
      if (scrollFrame) {
        startFrame = scrollFrame->GetScrolledFrame();
      }
      if (aDirection == nsIPresShell::eEither) {
        scrollFrame =
          nsLayoutUtils::GetNearestScrollableFrame(startFrame);
      } else {
        scrollFrame =
          nsLayoutUtils::GetNearestScrollableFrameForDirection(startFrame,
            aDirection == eVertical ? nsLayoutUtils::eVertical :
                                      nsLayoutUtils::eHorizontal);
      }
    }
  }
  if (!scrollFrame) {
    scrollFrame = GetRootScrollFrameAsScrollable();
  }
  return scrollFrame;
}

void
PresShell::CancelAllPendingReflows()
{
  mDirtyRoots.Clear();

  if (mReflowScheduled) {
    GetPresContext()->RefreshDriver()->RemoveLayoutFlushObserver(this);
    mReflowScheduled = false;
  }

  ASSERT_REFLOW_SCHEDULED_STATE();
}

nsresult
PresShell::RecreateFramesFor(nsIContent* aContent)
{
  NS_ENSURE_TRUE(mPresContext, NS_ERROR_FAILURE);
  if (!mDidInitialize) {
    // Nothing to do here.  In fact, if we proceed and aContent is the
    // root we will crash.
    return NS_OK;
  }

  // Don't call RecreateFramesForContent since that is not exported and we want
  // to keep the number of entrypoints down.

  NS_ASSERTION(mViewManager, "Should have view manager");

  // Have to make sure that the content notifications are flushed before we
  // start messing with the frame model; otherwise we can get content doubling.
  mDocument->FlushPendingNotifications(Flush_ContentAndNotify);

  nsAutoScriptBlocker scriptBlocker;

  nsStyleChangeList changeList;
  changeList.AppendChange(nullptr, aContent, nsChangeHint_ReconstructFrame);

  // Mark ourselves as not safe to flush while we're doing frame construction.
  ++mChangeNestCount;
  nsresult rv = mFrameConstructor->ProcessRestyledFrames(changeList);
  --mChangeNestCount;
  
  return rv;
}

void
nsIPresShell::PostRecreateFramesFor(Element* aElement)
{
  FrameConstructor()->PostRestyleEvent(aElement, nsRestyleHint(0),
                                       nsChangeHint_ReconstructFrame);
}

void
nsIPresShell::RestyleForAnimation(Element* aElement, nsRestyleHint aHint)
{
  FrameConstructor()->PostAnimationRestyleEvent(aElement, aHint,
                                                NS_STYLE_HINT_NONE);
}

void
PresShell::ClearFrameRefs(nsIFrame* aFrame)
{
  mPresContext->EventStateManager()->ClearFrameRefs(aFrame);

  nsWeakFrame* weakFrame = mWeakFrames;
  while (weakFrame) {
    nsWeakFrame* prev = weakFrame->GetPreviousWeakFrame();
    if (weakFrame->GetFrame() == aFrame) {
      // This removes weakFrame from mWeakFrames.
      weakFrame->Clear(this);
    }
    weakFrame = prev;
  }
}

already_AddRefed<nsRenderingContext>
PresShell::GetReferenceRenderingContext()
{
  nsDeviceContext* devCtx = mPresContext->DeviceContext();
  nsRefPtr<nsRenderingContext> rc;
  if (mPresContext->IsScreen()) {
    rc = new nsRenderingContext();
    rc->Init(devCtx, gfxPlatform::GetPlatform()->ScreenReferenceSurface());
  } else {
    devCtx->CreateRenderingContext(*getter_AddRefs(rc));
  }
  return rc.forget();
}

nsresult
PresShell::GoToAnchor(const nsAString& aAnchorName, bool aScroll)
{
  if (!mDocument) {
    return NS_ERROR_FAILURE;
  }
  
  const Element *root = mDocument->GetRootElement();
  if (root && root->IsSVG(nsGkAtoms::svg)) {
    // We need to execute this even if there is an empty anchor name
    // so that any existing SVG fragment identifier effect is removed
    if (SVGFragmentIdentifier::ProcessFragmentIdentifier(mDocument, aAnchorName)) {
      return NS_OK;
    }
  }

  // Hold a reference to the ESM in case event dispatch tears us down.
  nsRefPtr<nsEventStateManager> esm = mPresContext->EventStateManager();

  if (aAnchorName.IsEmpty()) {
    NS_ASSERTION(!aScroll, "can't scroll to empty anchor name");
    esm->SetContentState(nullptr, NS_EVENT_STATE_URLTARGET);
    return NS_OK;
  }

  nsCOMPtr<nsIDOMHTMLDocument> htmlDoc = do_QueryInterface(mDocument);
  nsresult rv = NS_OK;
  nsCOMPtr<nsIContent> content;

  // Search for an element with a matching "id" attribute
  if (mDocument) {    
    content = mDocument->GetElementById(aAnchorName);
  }

  // Search for an anchor element with a matching "name" attribute
  if (!content && htmlDoc) {
    nsCOMPtr<nsIDOMNodeList> list;
    // Find a matching list of named nodes
    rv = htmlDoc->GetElementsByName(aAnchorName, getter_AddRefs(list));
    if (NS_SUCCEEDED(rv) && list) {
      uint32_t i;
      // Loop through the named nodes looking for the first anchor
      for (i = 0; true; i++) {
        nsCOMPtr<nsIDOMNode> node;
        rv = list->Item(i, getter_AddRefs(node));
        if (!node) {  // End of list
          break;
        }
        // Ensure it's an anchor element
        content = do_QueryInterface(node);
        if (content) {
          if (content->Tag() == nsGkAtoms::a && content->IsHTML()) {
            break;
          }
          content = nullptr;
        }
      }
    }
  }

  // Search for anchor in the HTML namespace with a matching name
  if (!content && !htmlDoc)
  {
    nsCOMPtr<nsIDOMDocument> doc = do_QueryInterface(mDocument);
    nsCOMPtr<nsIDOMNodeList> list;
    NS_NAMED_LITERAL_STRING(nameSpace, "http://www.w3.org/1999/xhtml");
    // Get the list of anchor elements
    rv = doc->GetElementsByTagNameNS(nameSpace, NS_LITERAL_STRING("a"), getter_AddRefs(list));
    if (NS_SUCCEEDED(rv) && list) {
      uint32_t i;
      // Loop through the named nodes looking for the first anchor
      for (i = 0; true; i++) {
        nsCOMPtr<nsIDOMNode> node;
        rv = list->Item(i, getter_AddRefs(node));
        if (!node) { // End of list
          break;
        }
        // Compare the name attribute
        nsCOMPtr<nsIDOMElement> element = do_QueryInterface(node);
        nsAutoString value;
        if (element && NS_SUCCEEDED(element->GetAttribute(NS_LITERAL_STRING("name"), value))) {
          if (value.Equals(aAnchorName)) {
            content = do_QueryInterface(element);
            break;
          }
        }
      }
    }
  }

  esm->SetContentState(content, NS_EVENT_STATE_URLTARGET);

#ifdef ACCESSIBILITY
  nsIContent *anchorTarget = content;
#endif

  if (content) {
    if (aScroll) {
      rv = ScrollContentIntoView(content,
                                 ScrollAxis(SCROLL_TOP, SCROLL_ALWAYS),
                                 ScrollAxis(),
                                 ANCHOR_SCROLL_FLAGS);
      NS_ENSURE_SUCCESS(rv, rv);

      nsIScrollableFrame* rootScroll = GetRootScrollFrameAsScrollable();
      if (rootScroll) {
        mLastAnchorScrolledTo = content;
        mLastAnchorScrollPositionY = rootScroll->GetScrollPosition().y;
      }
    }

    // Should we select the target? This action is controlled by a
    // preference: the default is to not select.
    bool selectAnchor = Preferences::GetBool("layout.selectanchor");

    // Even if select anchor pref is false, we must still move the
    // caret there. That way tabbing will start from the new
    // location
    nsRefPtr<nsIDOMRange> jumpToRange = new nsRange();
    while (content && content->GetFirstChild()) {
      content = content->GetFirstChild();
    }
    nsCOMPtr<nsIDOMNode> node(do_QueryInterface(content));
    NS_ASSERTION(node, "No nsIDOMNode for descendant of anchor");
    jumpToRange->SelectNodeContents(node);
    // Select the anchor
    nsISelection* sel = mSelection->
      GetSelection(nsISelectionController::SELECTION_NORMAL);
    if (sel) {
      sel->RemoveAllRanges();
      sel->AddRange(jumpToRange);
      if (!selectAnchor) {
        // Use a caret (collapsed selection) at the start of the anchor
        sel->CollapseToStart();
      }
    }
    // Selection is at anchor.
    // Now focus the document itself if focus is on an element within it.
    nsPIDOMWindow *win = mDocument->GetWindow();

    nsIFocusManager* fm = nsFocusManager::GetFocusManager();
    if (fm && win) {
      nsCOMPtr<nsIDOMWindow> focusedWindow;
      fm->GetFocusedWindow(getter_AddRefs(focusedWindow));
      if (SameCOMIdentity(win, focusedWindow)) {
        fm->ClearFocus(focusedWindow);
      }
    }

    // If the target is an animation element, activate the animation
    if (content->IsNodeOfType(nsINode::eANIMATION)) {
      SVGContentUtils::ActivateByHyperlink(content.get());
    }
  } else {
    rv = NS_ERROR_FAILURE;
    NS_NAMED_LITERAL_STRING(top, "top");
    if (nsContentUtils::EqualsIgnoreASCIICase(aAnchorName, top)) {
      // Scroll to the top/left if aAnchorName is "top" and there is no element
      // with such a name or id.
      rv = NS_OK;
      nsIScrollableFrame* sf = GetRootScrollFrameAsScrollable();
      // Check |aScroll| after setting |rv| so we set |rv| to the same
      // thing whether or not |aScroll| is true.
      if (aScroll && sf) {
        // Scroll to the top of the page
        sf->ScrollTo(nsPoint(0, 0), nsIScrollableFrame::INSTANT);
      }
    }
  }

#ifdef ACCESSIBILITY
  if (anchorTarget) {
    nsAccessibilityService* accService = AccService();
    if (accService)
      accService->NotifyOfAnchorJumpTo(anchorTarget);
  }
#endif

  return rv;
}

nsresult
PresShell::ScrollToAnchor()
{
  if (!mLastAnchorScrolledTo)
    return NS_OK;

  NS_ASSERTION(mDidInitialize, "should have done initial reflow by now");

  nsIScrollableFrame* rootScroll = GetRootScrollFrameAsScrollable();
  if (!rootScroll ||
      mLastAnchorScrollPositionY != rootScroll->GetScrollPosition().y)
    return NS_OK;

  nsresult rv = ScrollContentIntoView(mLastAnchorScrolledTo,
                                      ScrollAxis(SCROLL_TOP, SCROLL_ALWAYS),
                                      ScrollAxis(),
                                      ANCHOR_SCROLL_FLAGS);
  mLastAnchorScrolledTo = nullptr;
  return rv;
}

/*
 * Helper (per-continuation) for ScrollContentIntoView.
 *
 * @param aContainerFrame [in] the frame which aRect is relative to
 * @param aFrame [in] Frame whose bounds should be unioned
 * @param aUseWholeLineHeightForInlines [in] if true, then for inline frames
 * we should include the top of the line in the added rectangle
 * @param aRect [inout] rect into which its bounds should be unioned
 * @param aHaveRect [inout] whether aRect contains data yet
 * @param aPrevBlock [inout] the block aLines is a line iterator for
 * @param aLines [inout] the line iterator we're using
 * @param aCurLine [inout] the line to start looking from in this iterator
 */
static void
AccumulateFrameBounds(nsIFrame* aContainerFrame,
                      nsIFrame* aFrame,
                      bool aUseWholeLineHeightForInlines,
                      nsRect& aRect,
                      bool& aHaveRect,
                      nsIFrame*& aPrevBlock,
                      nsAutoLineIterator& aLines,
                      int32_t& aCurLine)
{
  nsIFrame* frame = aFrame;
  nsRect frameBounds = nsRect(nsPoint(0, 0), aFrame->GetSize());

  // If this is an inline frame and either the bounds height is 0 (quirks
  // layout model) or aUseWholeLineHeightForInlines is set, we need to
  // change the top of the bounds to include the whole line.
  if (frameBounds.height == 0 || aUseWholeLineHeightForInlines) {
    nsIFrame *prevFrame = aFrame;
    nsIFrame *f = aFrame;

    while (f && f->IsFrameOfType(nsIFrame::eLineParticipant) &&
           !f->IsTransformed() && !f->IsPositioned()) {
      prevFrame = f;
      f = prevFrame->GetParent();
    }

    if (f != aFrame &&
        f &&
        f->GetType() == nsGkAtoms::blockFrame) {
      // find the line containing aFrame and increase the top of |offset|.
      if (f != aPrevBlock) {
        aLines = f->GetLineIterator();
        aPrevBlock = f;
        aCurLine = 0;
      }
      if (aLines) {
        int32_t index = aLines->FindLineContaining(prevFrame, aCurLine);
        if (index >= 0) {
          aCurLine = index;
          nsIFrame *trash1;
          int32_t trash2;
          nsRect lineBounds;
          uint32_t trash3;

          if (NS_SUCCEEDED(aLines->GetLine(index, &trash1, &trash2,
                                           lineBounds, &trash3))) {
            frameBounds += frame->GetOffsetTo(f);
            frame = f;
            if (lineBounds.y < frameBounds.y) {
              frameBounds.height = frameBounds.YMost() - lineBounds.y;
              frameBounds.y = lineBounds.y;
            }
          }
        }
      }
    }
  }

  nsRect transformedBounds = nsLayoutUtils::TransformFrameRectToAncestor(frame,
    frameBounds, aContainerFrame);

  if (aHaveRect) {
    // We can't use nsRect::UnionRect since it drops empty rects on
    // the floor, and we need to include them.  (Thus we need
    // aHaveRect to know when to drop the initial value on the floor.)
    aRect.UnionRectEdges(aRect, transformedBounds);
  } else {
    aHaveRect = true;
    aRect = transformedBounds;
  }
}

static bool
ComputeNeedToScroll(nsIPresShell::WhenToScroll aWhenToScroll,
                    nscoord                    aLineSize,
                    nscoord                    aRectMin,
                    nscoord                    aRectMax,
                    nscoord                    aViewMin,
                    nscoord                    aViewMax) {
  // See how the rect should be positioned vertically
  if (nsIPresShell::SCROLL_ALWAYS == aWhenToScroll) {
    // The caller wants the frame as visible as possible
    return true;
  } else if (nsIPresShell::SCROLL_IF_NOT_VISIBLE == aWhenToScroll) {
    // Scroll only if no part of the frame is visible in this view
    return aRectMax - aLineSize <= aViewMin ||
           aRectMin + aLineSize >= aViewMax;
  } else if (nsIPresShell::SCROLL_IF_NOT_FULLY_VISIBLE == aWhenToScroll) {
    // Scroll only if part of the frame is hidden and more can fit in view
    return !(aRectMin >= aViewMin && aRectMax <= aViewMax) &&
      NS_MIN(aViewMax, aRectMax) - NS_MAX(aRectMin, aViewMin) < aViewMax - aViewMin;
  }
  return false;
}

static nscoord
ComputeWhereToScroll(int16_t aWhereToScroll,
                     nscoord aOriginalCoord,
                     nscoord aRectMin,
                     nscoord aRectMax,
                     nscoord aViewMin,
                     nscoord aViewMax,
                     nscoord* aRangeMin,
                     nscoord* aRangeMax) {
  nscoord resultCoord = aOriginalCoord;
  // Allow the scroll operation to land anywhere that
  // makes the whole rectangle visible.
  if (nsIPresShell::SCROLL_MINIMUM == aWhereToScroll) {
    if (aRectMin < aViewMin) {
      // Scroll up so the frame's top edge is visible
      resultCoord = aRectMin;
    } else if (aRectMax > aViewMax) {
      // Scroll down so the frame's bottom edge is visible. Make sure the
      // frame's top edge is still visible
      resultCoord = aOriginalCoord + aRectMax - aViewMax;
      if (resultCoord > aRectMin) {
        resultCoord = aRectMin;
      }
    }
  } else {
    nscoord frameAlignCoord =
      NSToCoordRound(aRectMin + (aRectMax - aRectMin) * (aWhereToScroll / 100.0f));
    resultCoord =  NSToCoordRound(frameAlignCoord - (aViewMax - aViewMin) * (
                                  aWhereToScroll / 100.0f));
  }
  nscoord scrollPortLength = aViewMax - aViewMin;
  // Force the scroll range to extend to include resultCoord.
  *aRangeMin = NS_MIN(resultCoord, aRectMax - scrollPortLength);
  *aRangeMax = NS_MAX(resultCoord, aRectMin);
  return resultCoord;
}

/**
 * This function takes a scrollable frame, a rect in the coordinate system
 * of the scrolled frame, and a desired percentage-based scroll
 * position and attempts to scroll the rect to that position in the
 * scrollport.
 * 
 * This needs to work even if aRect has a width or height of zero.
 */
static void ScrollToShowRect(nsIScrollableFrame*      aScrollFrame,
                             const nsRect&            aRect,
                             nsIPresShell::ScrollAxis aVertical,
                             nsIPresShell::ScrollAxis aHorizontal,
                             uint32_t                 aFlags)
{
  nsPoint scrollPt = aScrollFrame->GetScrollPosition();
  nsRect visibleRect(scrollPt,
                     aScrollFrame->GetScrollPositionClampingScrollPortSize());

  nsSize lineSize;
  // Don't call GetLineScrollAmount unless we actually need it. Not only
  // does this save time, but it's not safe to call GetLineScrollAmount
  // during reflow (because it depends on font size inflation and doesn't
  // use the in-reflow-safe font-size inflation path). If we did call it,
  // it would assert and possible give the wrong result.
  if (aVertical.mWhenToScroll == nsIPresShell::SCROLL_IF_NOT_VISIBLE ||
      aHorizontal.mWhenToScroll == nsIPresShell::SCROLL_IF_NOT_VISIBLE) {
    lineSize = aScrollFrame->GetLineScrollAmount();
  }
  nsPresContext::ScrollbarStyles ss = aScrollFrame->GetScrollbarStyles();
  nsRect allowedRange(scrollPt, nsSize(0, 0));
  bool needToScroll = false;
  uint32_t directions = aScrollFrame->GetPerceivedScrollingDirections();

  if (((aFlags & nsIPresShell::SCROLL_OVERFLOW_HIDDEN) ||
       ss.mVertical != NS_STYLE_OVERFLOW_HIDDEN) &&
      (!aVertical.mOnlyIfPerceivedScrollableDirection ||
       (directions & nsIScrollableFrame::VERTICAL))) {

    if (ComputeNeedToScroll(aVertical.mWhenToScroll,
                            lineSize.height,
                            aRect.y,
                            aRect.YMost(),
                            visibleRect.y,
                            visibleRect.YMost())) {
      nscoord maxHeight;
      scrollPt.y = ComputeWhereToScroll(aVertical.mWhereToScroll,
                                        scrollPt.y,
                                        aRect.y,
                                        aRect.YMost(),
                                        visibleRect.y,
                                        visibleRect.YMost(),
                                        &allowedRange.y, &maxHeight);
      allowedRange.height = maxHeight - allowedRange.y;
      needToScroll = true;
    }
  }

  if (((aFlags & nsIPresShell::SCROLL_OVERFLOW_HIDDEN) ||
       ss.mHorizontal != NS_STYLE_OVERFLOW_HIDDEN) &&
      (!aHorizontal.mOnlyIfPerceivedScrollableDirection ||
       (directions & nsIScrollableFrame::HORIZONTAL))) {

    if (ComputeNeedToScroll(aHorizontal.mWhenToScroll,
                            lineSize.width,
                            aRect.x,
                            aRect.XMost(),
                            visibleRect.x,
                            visibleRect.XMost())) {
      nscoord maxWidth;
      scrollPt.x = ComputeWhereToScroll(aHorizontal.mWhereToScroll,
                                        scrollPt.x,
                                        aRect.x,
                                        aRect.XMost(),
                                        visibleRect.x,
                                        visibleRect.XMost(),
                                        &allowedRange.x, &maxWidth);
      allowedRange.width = maxWidth - allowedRange.x;
      needToScroll = true;
    }
  }

  // If we don't need to scroll, then don't try since it might cancel
  // a current smooth scroll operation.
  if (needToScroll) {
    aScrollFrame->ScrollTo(scrollPt, nsIScrollableFrame::INSTANT, &allowedRange);
  }
}

static void
DeleteScrollIntoViewData(void* aObject, nsIAtom* aPropertyName,
                         void* aPropertyValue, void* aData)
{
  PresShell::ScrollIntoViewData* data =
    static_cast<PresShell::ScrollIntoViewData*>(aPropertyValue);
  delete data;
}

nsresult
PresShell::ScrollContentIntoView(nsIContent*              aContent,
                                 nsIPresShell::ScrollAxis aVertical,
                                 nsIPresShell::ScrollAxis aHorizontal,
                                 uint32_t                 aFlags)
{
  NS_ENSURE_TRUE(aContent, NS_ERROR_NULL_POINTER);
  nsCOMPtr<nsIDocument> currentDoc = aContent->GetCurrentDoc();
  NS_ENSURE_STATE(currentDoc);

  NS_ASSERTION(mDidInitialize, "should have done initial reflow by now");

  if (mContentToScrollTo) {
    mContentToScrollTo->DeleteProperty(nsGkAtoms::scrolling);
  }
  mContentToScrollTo = aContent;
  ScrollIntoViewData* data = new ScrollIntoViewData();
  data->mContentScrollVAxis = aVertical;
  data->mContentScrollHAxis = aHorizontal;
  data->mContentToScrollToFlags = aFlags;
  if (NS_FAILED(mContentToScrollTo->SetProperty(nsGkAtoms::scrolling, data,
                                                ::DeleteScrollIntoViewData))) {
    mContentToScrollTo = nullptr;
  }

  // Flush layout and attempt to scroll in the process.
  currentDoc->SetNeedLayoutFlush();
  currentDoc->FlushPendingNotifications(Flush_InterruptibleLayout);

  // If mContentToScrollTo is non-null, that means we interrupted the reflow
  // (or suppressed it altogether because we're suppressing interruptible
  // flushes right now) and won't necessarily get the position correct, but do
  // a best-effort scroll here.  The other option would be to do this inside
  // FlushPendingNotifications, but I'm not sure the repeated scrolling that
  // could trigger if reflows keep getting interrupted would be more desirable
  // than a single best-effort scroll followed by one final scroll on the first
  // completed reflow.
  if (mContentToScrollTo) {
    DoScrollContentIntoView();
  }
  return NS_OK;
}

void
PresShell::DoScrollContentIntoView()
{
  NS_ASSERTION(mDidInitialize, "should have done initial reflow by now");

  nsIFrame* frame = mContentToScrollTo->GetPrimaryFrame();
  if (!frame) {
    mContentToScrollTo->DeleteProperty(nsGkAtoms::scrolling);
    mContentToScrollTo = nullptr;
    return;
  }

  if (frame->GetStateBits() & NS_FRAME_FIRST_REFLOW) {
    // The reflow flush before this scroll got interrupted, and this frame's
    // coords and size are all zero, and it has no content showing anyway.
    // Don't bother scrolling to it.  We'll try again when we finish up layout.
    return;
  }

  // Make sure we skip 'frame' ... if it's scrollable, we should use its
  // scrollable ancestor as the container.
  nsIFrame* container =
    nsLayoutUtils::GetClosestFrameOfType(frame->GetParent(), nsGkAtoms::scrollFrame);
  if (!container) {
    // nothing can be scrolled
    return;
  }

  ScrollIntoViewData* data = static_cast<ScrollIntoViewData*>(
    mContentToScrollTo->GetProperty(nsGkAtoms::scrolling));
  if (MOZ_UNLIKELY(!data)) {
    mContentToScrollTo = nullptr;
    return;
  }

  // This is a two-step process.
  // Step 1: Find the bounds of the rect we want to scroll into view.  For
  //         example, for an inline frame we may want to scroll in the whole
  //         line, or we may want to scroll multiple lines into view.
  // Step 2: Walk container frame and its ancestors and scroll them
  //         appropriately.
  // frameBounds is relative to container. We're assuming
  // that scrollframes don't split so every continuation of frame will
  // be a descendant of container. (Things would still mostly work
  // even if that assumption was false.)
  nsRect frameBounds;
  bool haveRect = false;
  bool useWholeLineHeightForInlines =
    data->mContentScrollVAxis.mWhenToScroll != nsIPresShell::SCROLL_IF_NOT_FULLY_VISIBLE;
  // Reuse the same line iterator across calls to AccumulateFrameBounds.  We set
  // it every time we detect a new block (stored in prevBlock).
  nsIFrame* prevBlock = nullptr;
  nsAutoLineIterator lines;
  // The last line we found a continuation on in |lines|.  We assume that later
  // continuations cannot come on earlier lines.
  int32_t curLine = 0;
  do {
    AccumulateFrameBounds(container, frame, useWholeLineHeightForInlines,
                          frameBounds, haveRect, prevBlock, lines, curLine);
  } while ((frame = frame->GetNextContinuation()));

  ScrollFrameRectIntoView(container, frameBounds, data->mContentScrollVAxis,
                          data->mContentScrollHAxis,
                          data->mContentToScrollToFlags);
}

bool
PresShell::ScrollFrameRectIntoView(nsIFrame*                aFrame,
                                   const nsRect&            aRect,
                                   nsIPresShell::ScrollAxis aVertical,
                                   nsIPresShell::ScrollAxis aHorizontal,
                                   uint32_t                 aFlags)
{
  bool didScroll = false;
  // This function needs to work even if rect has a width or height of 0.
  nsRect rect = aRect;
  nsIFrame* container = aFrame;
  // Walk up the frame hierarchy scrolling the rect into view and
  // keeping rect relative to container
  do {
    nsIScrollableFrame* sf = do_QueryFrame(container);
    if (sf) {
      nsPoint oldPosition = sf->GetScrollPosition();
      ScrollToShowRect(sf, rect - sf->GetScrolledFrame()->GetPosition(),
                       aVertical, aHorizontal, aFlags);
      nsPoint newPosition = sf->GetScrollPosition();
      // If the scroll position increased, that means our content moved up,
      // so our rect's offset should decrease
      rect += oldPosition - newPosition;

      if (oldPosition != newPosition) {
        didScroll = true;
      }

      // only scroll one container when this flag is set
      if (aFlags & nsIPresShell::SCROLL_FIRST_ANCESTOR_ONLY) {
        break;
      }
    }
    nsIFrame* parent;
    if (container->IsTransformed()) {
      container->GetTransformMatrix(nullptr, &parent);
      rect = nsLayoutUtils::TransformFrameRectToAncestor(container, rect, parent);
    } else {
      rect += container->GetPosition();
      parent = container->GetParent();
    }
    if (!parent && !(aFlags & nsIPresShell::SCROLL_NO_PARENT_FRAMES)) {
      nsPoint extraOffset(0,0);
      parent = nsLayoutUtils::GetCrossDocParentFrame(container, &extraOffset);
      if (parent) {
        int32_t APD = container->PresContext()->AppUnitsPerDevPixel();        
        int32_t parentAPD = parent->PresContext()->AppUnitsPerDevPixel();
        rect = rect.ConvertAppUnitsRoundOut(APD, parentAPD);
        rect += extraOffset;
      }
    }
    container = parent;
  } while (container);

  return didScroll;
}

nsRectVisibility
PresShell::GetRectVisibility(nsIFrame* aFrame,
                             const nsRect &aRect,
                             nscoord aMinTwips) const
{
  NS_ASSERTION(aFrame->PresContext() == GetPresContext(),
               "prescontext mismatch?");
  nsIFrame* rootFrame = mFrameConstructor->GetRootFrame();
  NS_ASSERTION(rootFrame,
               "How can someone have a frame for this presshell when there's no root?");
  nsIScrollableFrame* sf = GetRootScrollFrameAsScrollable();
  nsRect scrollPortRect;
  if (sf) {
    scrollPortRect = sf->GetScrollPortRect();
    nsIFrame* f = do_QueryFrame(sf);
    scrollPortRect += f->GetOffsetTo(rootFrame);
  } else {
    scrollPortRect = nsRect(nsPoint(0,0), rootFrame->GetSize());
  }

  nsRect r = aRect + aFrame->GetOffsetTo(rootFrame);
  // If aRect is entirely visible then we don't need to ensure that
  // at least aMinTwips of it is visible
  if (scrollPortRect.Contains(r))
    return nsRectVisibility_kVisible;

  nsRect insetRect = scrollPortRect;
  insetRect.Deflate(aMinTwips, aMinTwips);
  if (r.YMost() <= insetRect.y)
    return nsRectVisibility_kAboveViewport;
  if (r.y >= insetRect.YMost())
    return nsRectVisibility_kBelowViewport;
  if (r.XMost() <= insetRect.x)
    return nsRectVisibility_kLeftOfViewport;
  if (r.x >= insetRect.XMost())
    return nsRectVisibility_kRightOfViewport;

  return nsRectVisibility_kVisible;
}

void
PresShell::ScheduleViewManagerFlush()
{
  nsPresContext* presContext = GetPresContext();
  if (presContext) {
    presContext->RefreshDriver()->ScheduleViewManagerFlush();
  }
  if (mDocument) {
    mDocument->SetNeedLayoutFlush();
  }
}

void
PresShell::DispatchSynthMouseMove(nsGUIEvent *aEvent,
                                  bool aFlushOnHoverChange)
{
  uint32_t hoverGenerationBefore = mFrameConstructor->GetHoverGeneration();
  nsEventStatus status;
  nsIView* targetView = nsIView::GetViewFor(aEvent->widget);
  targetView->GetViewManager()->DispatchEvent(aEvent, targetView, &status);
  if (aFlushOnHoverChange &&
      hoverGenerationBefore != mFrameConstructor->GetHoverGeneration()) {
    // Flush so that the resulting reflow happens now so that our caller
    // can suppress any synthesized mouse moves caused by that reflow.
    FlushPendingNotifications(Flush_Layout);
  }
}

void
PresShell::ClearMouseCaptureOnView(nsIView* aView)
{
  if (gCaptureInfo.mContent) {
    if (aView) {
      // if a view was specified, ensure that the captured content is within
      // this view.
      nsIFrame* frame = gCaptureInfo.mContent->GetPrimaryFrame();
      if (frame) {
        nsIView* view = frame->GetClosestView();
        // if there is no view, capturing won't be handled any more, so
        // just release the capture.
        if (view) {
          do {
            if (view == aView) {
              NS_RELEASE(gCaptureInfo.mContent);
              // the view containing the captured content likely disappeared so
              // disable capture for now.
              gCaptureInfo.mAllowed = false;
              break;
            }

            view = view->GetParent();
          } while (view);
          // return if the view wasn't found
          return;
        }
      }
    }

    NS_RELEASE(gCaptureInfo.mContent);
  }

  // disable mouse capture until the next mousedown as a dialog has opened
  // or a drag has started. Otherwise, someone could start capture during
  // the modal dialog or drag.
  gCaptureInfo.mAllowed = false;
}

void
nsIPresShell::ClearMouseCapture(nsIFrame* aFrame)
{
  if (!gCaptureInfo.mContent) {
    gCaptureInfo.mAllowed = false;
    return;
  }

  // null frame argument means clear the capture
  if (!aFrame) {
    NS_RELEASE(gCaptureInfo.mContent);
    gCaptureInfo.mAllowed = false;
    return;
  }

  nsIFrame* capturingFrame = gCaptureInfo.mContent->GetPrimaryFrame();
  if (!capturingFrame) {
    NS_RELEASE(gCaptureInfo.mContent);
    gCaptureInfo.mAllowed = false;
    return;
  }

  if (nsLayoutUtils::IsAncestorFrameCrossDoc(aFrame, capturingFrame)) {
    NS_RELEASE(gCaptureInfo.mContent);
    gCaptureInfo.mAllowed = false;
  }
}

nsresult
PresShell::CaptureHistoryState(nsILayoutHistoryState** aState, bool aLeavingPage)
{
  nsresult rv = NS_OK;

  NS_PRECONDITION(nullptr != aState, "null state pointer");

  // We actually have to mess with the docshell here, since we want to
  // store the state back in it.
  // XXXbz this isn't really right, since this is being called in the
  // content viewer's Hide() method...  by that point the docshell's
  // state could be wrong.  We should sort out a better ownership
  // model for the layout history state.
  nsCOMPtr<nsISupports> container = mPresContext->GetContainer();
  if (!container)
    return NS_ERROR_FAILURE;

  nsCOMPtr<nsIDocShell> docShell(do_QueryInterface(container));
  if (!docShell)
    return NS_ERROR_FAILURE;

  nsCOMPtr<nsILayoutHistoryState> historyState;
  docShell->GetLayoutHistoryState(getter_AddRefs(historyState));
  if (!historyState) {
    // Create the document state object
    rv = NS_NewLayoutHistoryState(getter_AddRefs(historyState));
  
    if (NS_FAILED(rv)) { 
      *aState = nullptr;
      return rv;
    }    

    docShell->SetLayoutHistoryState(historyState);
  }

  *aState = historyState;
  NS_IF_ADDREF(*aState);
  
  // Capture frame state for the entire frame hierarchy
  nsIFrame* rootFrame = mFrameConstructor->GetRootFrame();
  if (!rootFrame) return NS_OK;
  // Capture frame state for the root scroll frame
  // Don't capture state when first creating doc element hierarchy
  // As the scroll position is 0 and this will cause us to lose
  // our previously saved place!
  if (aLeavingPage) {
    nsIFrame* scrollFrame = GetRootScrollFrame();
    if (scrollFrame) {
      mFrameConstructor->CaptureFrameStateFor(scrollFrame, historyState,
                                              nsIStatefulFrame::eDocumentScrollState);
    }
  }

  mFrameConstructor->CaptureFrameState(rootFrame, historyState);  
 
  return NS_OK;
}

void
PresShell::UnsuppressAndInvalidate()
{
  // Note: We ignore the EnsureVisible check for resource documents, because
  // they won't have a docshell, so they'll always fail EnsureVisible.
  if ((!mDocument->IsResourceDoc() && !mPresContext->EnsureVisible()) ||
      mHaveShutDown) {
    // No point; we're about to be torn down anyway.
    return;
  }

  if (!mDocument->IsResourceDoc()) {
    // Notify observers that a new page is about to be drawn. Execute this
    // as soon as it is safe to run JS, which is guaranteed to be before we
    // go back to the event loop and actually draw the page.
    nsContentUtils::AddScriptRunner(new nsBeforeFirstPaintDispatcher(mDocument));
  }

  mPaintingSuppressed = false;
  nsIFrame* rootFrame = mFrameConstructor->GetRootFrame();
  if (rootFrame) {
    // let's assume that outline on a root frame is not supported
    rootFrame->InvalidateFrame();

    if (mCaretEnabled && mCaret) {
      mCaret->CheckCaretDrawingState();
    }
  }

  // now that painting is unsuppressed, focus may be set on the document
  nsPIDOMWindow *win = mDocument->GetWindow();
  if (win)
    win->SetReadyForFocus();

  if (!mHaveShutDown)
    SynthesizeMouseMove(false);
}

void
PresShell::UnsuppressPainting()
{
  if (mPaintSuppressionTimer) {
    mPaintSuppressionTimer->Cancel();
    mPaintSuppressionTimer = nullptr;
  }

  if (mIsDocumentGone || !mPaintingSuppressed)
    return;

  // If we have reflows pending, just wait until we process
  // the reflows and get all the frames where we want them
  // before actually unlocking the painting.  Otherwise
  // go ahead and unlock now.
  if (!mDirtyRoots.IsEmpty())
    mShouldUnsuppressPainting = true;
  else
    UnsuppressAndInvalidate();
}

// Post a request to handle an arbitrary callback after reflow has finished.
nsresult
PresShell::PostReflowCallback(nsIReflowCallback* aCallback)
{
  void* result = AllocateMisc(sizeof(nsCallbackEventRequest));
  nsCallbackEventRequest* request = (nsCallbackEventRequest*)result;

  request->callback = aCallback;
  request->next = nullptr;

  if (mLastCallbackEventRequest) {
    mLastCallbackEventRequest = mLastCallbackEventRequest->next = request;
  } else {
    mFirstCallbackEventRequest = request;
    mLastCallbackEventRequest = request;
  }
 
  return NS_OK;
}

void
PresShell::CancelReflowCallback(nsIReflowCallback* aCallback)
{
   nsCallbackEventRequest* before = nullptr;
   nsCallbackEventRequest* node = mFirstCallbackEventRequest;
   while(node)
   {
      nsIReflowCallback* callback = node->callback;

      if (callback == aCallback) 
      {
        nsCallbackEventRequest* toFree = node;
        if (node == mFirstCallbackEventRequest) {
          node = node->next;
          mFirstCallbackEventRequest = node;
          NS_ASSERTION(before == nullptr, "impossible");
        } else {
          node = node->next;
          before->next = node;
        }

        if (toFree == mLastCallbackEventRequest) {
          mLastCallbackEventRequest = before;
        }

        FreeMisc(sizeof(nsCallbackEventRequest), toFree);
      } else {
        before = node;
        node = node->next;
      }
   }
}

void
PresShell::CancelPostedReflowCallbacks()
{
  while (mFirstCallbackEventRequest) {
    nsCallbackEventRequest* node = mFirstCallbackEventRequest;
    mFirstCallbackEventRequest = node->next;
    if (!mFirstCallbackEventRequest) {
      mLastCallbackEventRequest = nullptr;
    }
    nsIReflowCallback* callback = node->callback;
    FreeMisc(sizeof(nsCallbackEventRequest), node);
    if (callback) {
      callback->ReflowCallbackCanceled();
    }
  }
}

void
PresShell::HandlePostedReflowCallbacks(bool aInterruptible)
{
   bool shouldFlush = false;

   while (mFirstCallbackEventRequest) {
     nsCallbackEventRequest* node = mFirstCallbackEventRequest;
     mFirstCallbackEventRequest = node->next;
     if (!mFirstCallbackEventRequest) {
       mLastCallbackEventRequest = nullptr;
     }
     nsIReflowCallback* callback = node->callback;
     FreeMisc(sizeof(nsCallbackEventRequest), node);
     if (callback) {
       if (callback->ReflowFinished()) {
         shouldFlush = true;
       }
     }
   }

   mozFlushType flushType =
     aInterruptible ? Flush_InterruptibleLayout : Flush_Layout;
   if (shouldFlush)
     FlushPendingNotifications(flushType);
}

bool
PresShell::IsSafeToFlush() const
{
  // Not safe if we are reflowing or in the middle of frame construction
  bool isSafeToFlush = !mIsReflowing &&
                         !mChangeNestCount;

  if (isSafeToFlush) {
    // Not safe if we are painting
    nsIViewManager* viewManager = GetViewManager();
    if (viewManager) {
      bool isPainting = false;
      viewManager->IsPainting(isPainting);
      if (isPainting) {
        isSafeToFlush = false;
      }
    }
  }

  return isSafeToFlush;
}


void
PresShell::FlushPendingNotifications(mozFlushType aType)
{
  /**
   * VERY IMPORTANT: If you add some sort of new flushing to this
   * method, make sure to add the relevant SetNeedLayoutFlush or
   * SetNeedStyleFlush calls on the document.
   */

#ifdef MOZ_ENABLE_PROFILER_SPS
  static const char flushTypeNames[][20] = {
    "Content",
    "ContentAndNotify",
    "Style",
    "InterruptibleLayout",
    "Layout",
    "Display"
  };
  // Make sure that we don't miss things added to mozFlushType!
  MOZ_ASSERT(static_cast<uint32_t>(aType) <= ArrayLength(flushTypeNames));

  SAMPLE_LABEL_PRINTF("layout", "Flush", "(Flush_%s)",
                      flushTypeNames[aType - 1]);
#endif

#ifdef ACCESSIBILITY
#ifdef DEBUG
  nsAccessibilityService* accService = GetAccService();
  if (accService) {
    NS_ASSERTION(!accService->IsProcessingRefreshDriverNotification(),
                 "Flush during accessible tree update!");
  }
#endif
#endif

  NS_ASSERTION(aType >= Flush_Frames, "Why did we get called?");

  bool isSafeToFlush = IsSafeToFlush();

  // If layout could possibly trigger scripts, then it's only safe to flush if
  // it's safe to run script.
  bool hasHadScriptObject;
  if (mDocument->GetScriptHandlingObject(hasHadScriptObject) ||
      hasHadScriptObject) {
    isSafeToFlush = isSafeToFlush && nsContentUtils::IsSafeToRunScript();
  }

  NS_ASSERTION(!isSafeToFlush || mViewManager, "Must have view manager");
  // Make sure the view manager stays alive.
  nsCOMPtr<nsIViewManager> viewManagerDeathGrip = mViewManager;
  if (isSafeToFlush && mViewManager) {
    // Processing pending notifications can kill us, and some callers only
    // hold weak refs when calling FlushPendingNotifications().  :(
    nsCOMPtr<nsIPresShell> kungFuDeathGrip(this);

    if (mResizeEvent.IsPending()) {
      FireResizeEvent();
      if (mIsDestroying) {
        return;
      }
    }

    // We need to make sure external resource documents are flushed too (for
    // example, svg filters that reference a filter in an external document
    // need the frames in the external document to be constructed for the
    // filter to work). We only need external resources to be flushed when the
    // main document is flushing >= Flush_Frames, so we flush external
    // resources here instead of nsDocument::FlushPendingNotifications.
    mDocument->FlushExternalResources(aType);

    // Force flushing of any pending content notifications that might have
    // queued up while our event was pending.  That will ensure that we don't
    // construct frames for content right now that's still waiting to be
    // notified on,
    mDocument->FlushPendingNotifications(Flush_ContentAndNotify);

    // Process pending restyles, since any flush of the presshell wants
    // up-to-date style data.
    if (!mIsDestroying) {
      mViewManager->FlushDelayedResize(false);
      mPresContext->FlushPendingMediaFeatureValuesChanged();

      // Flush any pending update of the user font set, since that could
      // cause style changes (for updating ex/ch units, and to cause a
      // reflow).
      mPresContext->FlushUserFontSet();

      // Flush any requested SMIL samples.
      if (mDocument->HasAnimationController()) {
        mDocument->GetAnimationController()->FlushResampleRequests();
      }

      // The FlushResampleRequests() above flushed style changes.
      if (!mIsDestroying) {
        nsAutoScriptBlocker scriptBlocker;
        mFrameConstructor->CreateNeededFrames();
        mFrameConstructor->ProcessPendingRestyles();
      }
    }

    // Dispatch any 'animationstart' events those (or earlier) restyles
    // queued up.
    if (!mIsDestroying) {
      mPresContext->AnimationManager()->DispatchEvents();
    }

    // Process whatever XBL constructors those restyles queued up.  This
    // ensures that onload doesn't fire too early and that we won't do extra
    // reflows after those constructors run.
    if (!mIsDestroying) {
      mDocument->BindingManager()->ProcessAttachedQueue();
    }

    // Now those constructors or events might have posted restyle
    // events.  At the same time, we still need up-to-date style data.
    // In particular, reflow depends on style being completely up to
    // date.  If it's not, then style context reparenting, which can
    // happen during reflow, might suddenly pick up the new rules and
    // we'll end up with frames whose style doesn't match the frame
    // type.
    if (!mIsDestroying) {
      nsAutoScriptBlocker scriptBlocker;
      mFrameConstructor->CreateNeededFrames();
      mFrameConstructor->ProcessPendingRestyles();
    }


    // There might be more pending constructors now, but we're not going to
    // worry about them.  They can't be triggered during reflow, so we should
    // be good.

    if (aType >= (mSuppressInterruptibleReflows ? Flush_Layout : Flush_InterruptibleLayout) &&
        !mIsDestroying) {
      mFrameConstructor->RecalcQuotesAndCounters();
      mViewManager->FlushDelayedResize(true);
      if (ProcessReflowCommands(aType < Flush_Layout) && mContentToScrollTo) {
        // We didn't get interrupted.  Go ahead and scroll to our content
        DoScrollContentIntoView();
        if (mContentToScrollTo) {
          mContentToScrollTo->DeleteProperty(nsGkAtoms::scrolling);
          mContentToScrollTo = nullptr;
        }
      }
    } else if (!mIsDestroying && mSuppressInterruptibleReflows &&
               aType == Flush_InterruptibleLayout) {
      // We suppressed this flush, but the document thinks it doesn't
      // need to flush anymore.  Let it know what's really going on.
      mDocument->SetNeedLayoutFlush();
    }

    if (aType >= Flush_Layout) {
      if (!mIsDestroying) {
        mViewManager->UpdateWidgetGeometry();
      }
    }
  }
}

void
PresShell::CharacterDataChanged(nsIDocument *aDocument,
                                nsIContent*  aContent,
                                CharacterDataChangeInfo* aInfo)
{
  NS_PRECONDITION(!mIsDocumentGone, "Unexpected CharacterDataChanged");
  NS_PRECONDITION(aDocument == mDocument, "Unexpected aDocument");

  nsAutoCauseReflowNotifier crNotifier(this);

  if (mCaret) {
    // Invalidate the caret's current location before we call into the frame
    // constructor. It is important to do this now, and not wait until the
    // resulting reflow, because this call causes continuation frames of the
    // text frame the caret is in to forget what part of the content they
    // refer to, making it hard for them to return the correct continuation
    // frame to the caret.
    mCaret->InvalidateOutsideCaret();
  }

  // Call this here so it only happens for real content mutations and
  // not cases when the frame constructor calls its own methods to force
  // frame reconstruction.
  nsIContent *container = aContent->GetParent();
  uint32_t selectorFlags =
    container ? (container->GetFlags() & NODE_ALL_SELECTOR_FLAGS) : 0;
  if (selectorFlags != 0 && !aContent->IsRootOfAnonymousSubtree()) {
    Element* element = container->AsElement();
    if (aInfo->mAppend && !aContent->GetNextSibling())
      mFrameConstructor->RestyleForAppend(element, aContent);
    else
      mFrameConstructor->RestyleForInsertOrChange(element, aContent);
  }

  mFrameConstructor->CharacterDataChanged(aContent, aInfo);
  VERIFY_STYLE_TREE;
}

void
PresShell::ContentStateChanged(nsIDocument* aDocument,
                               nsIContent* aContent,
                               nsEventStates aStateMask)
{
  NS_PRECONDITION(!mIsDocumentGone, "Unexpected ContentStateChanged");
  NS_PRECONDITION(aDocument == mDocument, "Unexpected aDocument");

  if (mDidInitialize) {
    nsAutoCauseReflowNotifier crNotifier(this);
    mFrameConstructor->ContentStateChanged(aContent, aStateMask);
    VERIFY_STYLE_TREE;
  }
}

void
PresShell::DocumentStatesChanged(nsIDocument* aDocument,
                                 nsEventStates aStateMask)
{
  NS_PRECONDITION(!mIsDocumentGone, "Unexpected DocumentStatesChanged");
  NS_PRECONDITION(aDocument == mDocument, "Unexpected aDocument");

  if (mDidInitialize &&
      mStyleSet->HasDocumentStateDependentStyle(mPresContext,
                                                mDocument->GetRootElement(),
                                                aStateMask)) {
    mFrameConstructor->PostRestyleEvent(mDocument->GetRootElement(),
                                        eRestyle_Subtree, NS_STYLE_HINT_NONE);
    VERIFY_STYLE_TREE;
  }

  if (aStateMask.HasState(NS_DOCUMENT_STATE_WINDOW_INACTIVE)) {
    nsIFrame* root = mFrameConstructor->GetRootFrame();
    if (root) {
      FrameLayerBuilder::InvalidateAllLayersForFrame(root);
      if (root->HasView()) {
        root->GetView()->SetForcedRepaint(true);
      }
    }
  }
}

void
PresShell::AttributeWillChange(nsIDocument* aDocument,
                               Element*     aElement,
                               int32_t      aNameSpaceID,
                               nsIAtom*     aAttribute,
                               int32_t      aModType)
{
  NS_PRECONDITION(!mIsDocumentGone, "Unexpected AttributeWillChange");
  NS_PRECONDITION(aDocument == mDocument, "Unexpected aDocument");

  // XXXwaterson it might be more elegant to wait until after the
  // initial reflow to begin observing the document. That would
  // squelch any other inappropriate notifications as well.
  if (mDidInitialize) {
    nsAutoCauseReflowNotifier crNotifier(this);
    mFrameConstructor->AttributeWillChange(aElement, aNameSpaceID,
                                           aAttribute, aModType);
    VERIFY_STYLE_TREE;
  }
}

void
PresShell::AttributeChanged(nsIDocument* aDocument,
                            Element*     aElement,
                            int32_t      aNameSpaceID,
                            nsIAtom*     aAttribute,
                            int32_t      aModType)
{
  NS_PRECONDITION(!mIsDocumentGone, "Unexpected AttributeChanged");
  NS_PRECONDITION(aDocument == mDocument, "Unexpected aDocument");

  // XXXwaterson it might be more elegant to wait until after the
  // initial reflow to begin observing the document. That would
  // squelch any other inappropriate notifications as well.
  if (mDidInitialize) {
    nsAutoCauseReflowNotifier crNotifier(this);
    mFrameConstructor->AttributeChanged(aElement, aNameSpaceID,
                                        aAttribute, aModType);
    VERIFY_STYLE_TREE;
  }
}

void
PresShell::ContentAppended(nsIDocument *aDocument,
                           nsIContent* aContainer,
                           nsIContent* aFirstNewContent,
                           int32_t     aNewIndexInContainer)
{
  NS_PRECONDITION(!mIsDocumentGone, "Unexpected ContentAppended");
  NS_PRECONDITION(aDocument == mDocument, "Unexpected aDocument");
  NS_PRECONDITION(aContainer, "must have container");
  
  if (!mDidInitialize) {
    return;
  }
  
  nsAutoCauseReflowNotifier crNotifier(this);

  // Call this here so it only happens for real content mutations and
  // not cases when the frame constructor calls its own methods to force
  // frame reconstruction.
  mFrameConstructor->RestyleForAppend(aContainer->AsElement(), aFirstNewContent);

  mFrameConstructor->ContentAppended(aContainer, aFirstNewContent, true);
  VERIFY_STYLE_TREE;
}

void
PresShell::ContentInserted(nsIDocument* aDocument,
                           nsIContent*  aContainer,
                           nsIContent*  aChild,
                           int32_t      aIndexInContainer)
{
  NS_PRECONDITION(!mIsDocumentGone, "Unexpected ContentInserted");
  NS_PRECONDITION(aDocument == mDocument, "Unexpected aDocument");

  if (!mDidInitialize) {
    return;
  }
  
  nsAutoCauseReflowNotifier crNotifier(this);

  // Call this here so it only happens for real content mutations and
  // not cases when the frame constructor calls its own methods to force
  // frame reconstruction.
  if (aContainer)
    mFrameConstructor->RestyleForInsertOrChange(aContainer->AsElement(), aChild);

  mFrameConstructor->ContentInserted(aContainer, aChild, nullptr, true);
  VERIFY_STYLE_TREE;
}

void
PresShell::ContentRemoved(nsIDocument *aDocument,
                          nsIContent* aContainer,
                          nsIContent* aChild,
                          int32_t     aIndexInContainer,
                          nsIContent* aPreviousSibling)
{
  NS_PRECONDITION(!mIsDocumentGone, "Unexpected ContentRemoved");
  NS_PRECONDITION(aDocument == mDocument, "Unexpected aDocument");

  // Make sure that the caret doesn't leave a turd where the child used to be.
  if (mCaret) {
    mCaret->InvalidateOutsideCaret();
  }

  // Notify the ESM that the content has been removed, so that
  // it can clean up any state related to the content.
  mPresContext->EventStateManager()->ContentRemoved(aDocument, aChild);

  nsAutoCauseReflowNotifier crNotifier(this);

  // Call this here so it only happens for real content mutations and
  // not cases when the frame constructor calls its own methods to force
  // frame reconstruction.
  nsIContent* oldNextSibling;
  if (aContainer) {
    oldNextSibling = aContainer->GetChildAt(aIndexInContainer);
  } else {
    oldNextSibling = nullptr;
  }
  
  if (aContainer && aContainer->IsElement()) {
    mFrameConstructor->RestyleForRemove(aContainer->AsElement(), aChild,
                                        oldNextSibling);
  }

  bool didReconstruct;
  mFrameConstructor->ContentRemoved(aContainer, aChild, oldNextSibling,
                                    nsCSSFrameConstructor::REMOVE_CONTENT,
                                    &didReconstruct);

  VERIFY_STYLE_TREE;
}

nsresult
PresShell::ReconstructFrames(void)
{
  NS_PRECONDITION(!mFrameConstructor->GetRootFrame() || mDidInitialize,
                  "Must not have root frame before initial reflow");
  if (!mDidInitialize) {
    // Nothing to do here
    return NS_OK;
  }

  nsCOMPtr<nsIPresShell> kungFuDeathGrip(this);

  // Have to make sure that the content notifications are flushed before we
  // start messing with the frame model; otherwise we can get content doubling.
  mDocument->FlushPendingNotifications(Flush_ContentAndNotify);

  nsAutoCauseReflowNotifier crNotifier(this);
  mFrameConstructor->BeginUpdate();
  nsresult rv = mFrameConstructor->ReconstructDocElementHierarchy();
  VERIFY_STYLE_TREE;
  mFrameConstructor->EndUpdate();

  return rv;
}

void
nsIPresShell::ReconstructStyleDataInternal()
{
  mStylesHaveChanged = false;

  if (mIsDestroying) {
    // We don't want to mess with restyles at this point
    return;
  }

  if (mPresContext) {
    mPresContext->RebuildUserFontSet();
    mPresContext->AnimationManager()->KeyframesListIsDirty();
  }

  Element* root = mDocument->GetRootElement();
  if (!mDidInitialize) {
    // Nothing to do here, since we have no frames yet
    return;
  }

  if (!root) {
    // No content to restyle
    return;
  }
  
  mFrameConstructor->PostRestyleEvent(root, eRestyle_Subtree, NS_STYLE_HINT_NONE);
}

void
nsIPresShell::ReconstructStyleDataExternal()
{
  ReconstructStyleDataInternal();
}

void
PresShell::StyleSheetAdded(nsIDocument *aDocument,
                           nsIStyleSheet* aStyleSheet,
                           bool aDocumentSheet)
{
  // We only care when enabled sheets are added
  NS_PRECONDITION(aStyleSheet, "Must have a style sheet!");

  if (aStyleSheet->IsApplicable() && aStyleSheet->HasRules()) {
    mStylesHaveChanged = true;
  }
}

void 
PresShell::StyleSheetRemoved(nsIDocument *aDocument,
                             nsIStyleSheet* aStyleSheet,
                             bool aDocumentSheet)
{
  // We only care when enabled sheets are removed
  NS_PRECONDITION(aStyleSheet, "Must have a style sheet!");

  if (aStyleSheet->IsApplicable() && aStyleSheet->HasRules()) {
    mStylesHaveChanged = true;
  }
}

void
PresShell::StyleSheetApplicableStateChanged(nsIDocument *aDocument,
                                            nsIStyleSheet* aStyleSheet,
                                            bool aApplicable)
{
  if (aStyleSheet->HasRules()) {
    mStylesHaveChanged = true;
  }
}

void
PresShell::StyleRuleChanged(nsIDocument *aDocument,
                            nsIStyleSheet* aStyleSheet,
                            nsIStyleRule* aOldStyleRule,
                            nsIStyleRule* aNewStyleRule)
{
  mStylesHaveChanged = true;
}

void
PresShell::StyleRuleAdded(nsIDocument *aDocument,
                          nsIStyleSheet* aStyleSheet,
                          nsIStyleRule* aStyleRule) 
{
  mStylesHaveChanged = true;
}

void
PresShell::StyleRuleRemoved(nsIDocument *aDocument,
                            nsIStyleSheet* aStyleSheet,
                            nsIStyleRule* aStyleRule) 
{
  mStylesHaveChanged = true;
}

nsIFrame*
PresShell::GetRealPrimaryFrameFor(nsIContent* aContent) const
{
  if (aContent->GetDocument() != GetDocument()) {
    return nullptr;
  }
  nsIFrame *primaryFrame = aContent->GetPrimaryFrame();
  if (!primaryFrame)
    return nullptr;
  return nsPlaceholderFrame::GetRealFrameFor(primaryFrame);
}

nsIFrame*
PresShell::GetPlaceholderFrameFor(nsIFrame* aFrame) const
{
  return mFrameConstructor->GetPlaceholderFrameFor(aFrame);
}

nsresult
PresShell::RenderDocument(const nsRect& aRect, uint32_t aFlags,
                          nscolor aBackgroundColor,
                          gfxContext* aThebesContext)
{
  NS_ENSURE_TRUE(!(aFlags & RENDER_IS_UNTRUSTED), NS_ERROR_NOT_IMPLEMENTED);

  nsRootPresContext* rootPresContext = mPresContext->GetRootPresContext();
  if (rootPresContext) {
    rootPresContext->FlushWillPaintObservers();
    if (mIsDestroying)
      return NS_OK;
  }

  nsAutoScriptBlocker blockScripts;

  // Set up the rectangle as the path in aThebesContext
  gfxRect r(0, 0,
            nsPresContext::AppUnitsToFloatCSSPixels(aRect.width),
            nsPresContext::AppUnitsToFloatCSSPixels(aRect.height));
  aThebesContext->NewPath();
#ifdef MOZ_GFX_OPTIMIZE_MOBILE
  aThebesContext->Rectangle(r, true);
#else
  aThebesContext->Rectangle(r);
#endif

  nsIFrame* rootFrame = mFrameConstructor->GetRootFrame();
  if (!rootFrame) {
    // Nothing to paint, just fill the rect
    aThebesContext->SetColor(gfxRGBA(aBackgroundColor));
    aThebesContext->Fill();
    return NS_OK;
  }

  gfxContextAutoSaveRestore save(aThebesContext);

  gfxContext::GraphicsOperator oldOperator = aThebesContext->CurrentOperator();
  if (oldOperator == gfxContext::OPERATOR_OVER) {
    // Clip to the destination rectangle before we push the group,
    // to limit the size of the temporary surface
    aThebesContext->Clip();
  }

  // we want the window to be composited as a single image using
  // whatever operator was set; set OPERATOR_OVER here, which is
  // either already the case, or overrides the operator in a group.
  // the original operator will be present when we PopGroup.
  // we can avoid using a temporary surface if we're using OPERATOR_OVER
  // and our background color has no alpha (so we'll be compositing on top
  // of a fully opaque solid color region)
  bool needsGroup = NS_GET_A(aBackgroundColor) < 0xff ||
    oldOperator != gfxContext::OPERATOR_OVER;

  if (needsGroup) {
    aThebesContext->PushGroup(NS_GET_A(aBackgroundColor) == 0xff ?
                              gfxASurface::CONTENT_COLOR :
                              gfxASurface::CONTENT_COLOR_ALPHA);
    aThebesContext->Save();

    if (oldOperator != gfxContext::OPERATOR_OVER) {
      // Clip now while we paint to the temporary surface. For
      // non-source-bounded operators (e.g., SOURCE), we need to do clip
      // here after we've pushed the group, so that eventually popping
      // the group and painting it will be able to clear the entire
      // destination surface.
      aThebesContext->Clip();
      aThebesContext->SetOperator(gfxContext::OPERATOR_OVER);
    }
  }

  aThebesContext->Translate(gfxPoint(-nsPresContext::AppUnitsToFloatCSSPixels(aRect.x),
                                     -nsPresContext::AppUnitsToFloatCSSPixels(aRect.y)));

  nsDeviceContext* devCtx = mPresContext->DeviceContext();
  gfxFloat scale = gfxFloat(devCtx->AppUnitsPerDevPixel())/nsPresContext::AppUnitsPerCSSPixel();
  aThebesContext->Scale(scale, scale);

  // Since canvas APIs use floats to set up their matrices, we may have
  // some slight inaccuracy here. Adjust matrix components that are
  // integers up to the accuracy of floats to be those integers.
  aThebesContext->NudgeCurrentMatrixToIntegers();

  AutoSaveRestoreRenderingState _(this);

  nsRefPtr<nsRenderingContext> rc = new nsRenderingContext();
  rc->Init(devCtx, aThebesContext);

  bool wouldFlushRetainedLayers = false;
  uint32_t flags = nsLayoutUtils::PAINT_IGNORE_SUPPRESSION;
  if (aThebesContext->CurrentMatrix().HasNonIntegerTranslation()) {
    flags |= nsLayoutUtils::PAINT_IN_TRANSFORM;
  }
  if (!(aFlags & RENDER_ASYNC_DECODE_IMAGES)) {
    flags |= nsLayoutUtils::PAINT_SYNC_DECODE_IMAGES;
  }
  if (aFlags & RENDER_USE_WIDGET_LAYERS) {
    // We only support using widget layers on display root's with widgets.
    nsIView* view = rootFrame->GetView();
    if (view && view->GetWidget() &&
        nsLayoutUtils::GetDisplayRootFrame(rootFrame) == rootFrame) {
      flags |= nsLayoutUtils::PAINT_WIDGET_LAYERS;
    }
  }
  if (!(aFlags & RENDER_CARET)) {
    wouldFlushRetainedLayers = true;
    flags |= nsLayoutUtils::PAINT_HIDE_CARET;
  }
  if (aFlags & RENDER_IGNORE_VIEWPORT_SCROLLING) {
    wouldFlushRetainedLayers = !IgnoringViewportScrolling();
    mRenderFlags = ChangeFlag(mRenderFlags, true, STATE_IGNORING_VIEWPORT_SCROLLING);
  }
  if (aFlags & RENDER_DOCUMENT_RELATIVE) {
    // XXX be smarter about this ... drawWindow might want a rect
    // that's "pretty close" to what our retained layer tree covers.
    // In that case, it wouldn't disturb normal rendering too much,
    // and we should allow it.
    wouldFlushRetainedLayers = true;
    flags |= nsLayoutUtils::PAINT_DOCUMENT_RELATIVE;
  }

  // Don't let drawWindow blow away our retained layer tree
  if ((flags & nsLayoutUtils::PAINT_WIDGET_LAYERS) && wouldFlushRetainedLayers) {
    flags &= ~nsLayoutUtils::PAINT_WIDGET_LAYERS;
  }

  nsLayoutUtils::PaintFrame(rc, rootFrame, nsRegion(aRect),
                            aBackgroundColor, flags);

  // if we had to use a group, paint it to the destination now
  if (needsGroup) {
    aThebesContext->Restore();
    aThebesContext->PopGroupToSource();
    aThebesContext->Paint();
  }

  return NS_OK;
}

/*
 * Clip the display list aList to a range. Returns the clipped
 * rectangle surrounding the range.
 */
nsRect
PresShell::ClipListToRange(nsDisplayListBuilder *aBuilder,
                           nsDisplayList* aList,
                           nsRange* aRange)
{
  // iterate though the display items and add up the bounding boxes of each.
  // This will allow the total area of the frames within the range to be
  // determined. To do this, remove an item from the bottom of the list, check
  // whether it should be part of the range, and if so, append it to the top
  // of the temporary list tmpList. If the item is a text frame at the end of
  // the selection range, wrap it in an nsDisplayClip to clip the display to
  // the portion of the text frame that is part of the selection. Then, append
  // the wrapper to the top of the list. Otherwise, just delete the item and
  // don't append it.
  nsRect surfaceRect;
  nsDisplayList tmpList;

  nsDisplayItem* i;
  while ((i = aList->RemoveBottom())) {
    // itemToInsert indiciates the item that should be inserted into the
    // temporary list. If null, no item should be inserted.
    nsDisplayItem* itemToInsert = nullptr;
    nsIFrame* frame = i->GetUnderlyingFrame();
    if (frame) {
      nsIContent* content = frame->GetContent();
      if (content) {
        bool atStart = (content == aRange->GetStartParent());
        bool atEnd = (content == aRange->GetEndParent());
        if ((atStart || atEnd) && frame->GetType() == nsGkAtoms::textFrame) {
          int32_t frameStartOffset, frameEndOffset;
          frame->GetOffsets(frameStartOffset, frameEndOffset);

          int32_t hilightStart =
            atStart ? NS_MAX(aRange->StartOffset(), frameStartOffset) : frameStartOffset;
          int32_t hilightEnd =
            atEnd ? NS_MIN(aRange->EndOffset(), frameEndOffset) : frameEndOffset;
          if (hilightStart < hilightEnd) {
            // determine the location of the start and end edges of the range.
            nsPoint startPoint, endPoint;
            frame->GetPointFromOffset(hilightStart, &startPoint);
            frame->GetPointFromOffset(hilightEnd, &endPoint);

            // the clip rectangle is determined by taking the the start and
            // end points of the range, offset from the reference frame.
            // Because of rtl, the end point may be to the left of the
            // start point, so x is set to the lowest value
            nsRect textRect(aBuilder->ToReferenceFrame(frame), frame->GetSize());
            nscoord x = NS_MIN(startPoint.x, endPoint.x);
            textRect.x += x;
            textRect.width = NS_MAX(startPoint.x, endPoint.x) - x;
            surfaceRect.UnionRect(surfaceRect, textRect);

            // wrap the item in an nsDisplayClip so that it can be clipped to
            // the selection. If the allocation fails, fall through and delete
            // the item below.
            itemToInsert = new (aBuilder)
                nsDisplayClip(aBuilder, frame, i, textRect);
          }
        }
        // Don't try to descend into subdocuments.
        // If this ever changes we'd need to add handling for subdocuments with
        // different zoom levels.
        else if (content->GetCurrentDoc() ==
                   aRange->GetStartParent()->GetCurrentDoc()) {
          // if the node is within the range, append it to the temporary list
          bool before, after;
          nsresult rv =
            nsRange::CompareNodeToRange(content, aRange, &before, &after);
          if (NS_SUCCEEDED(rv) && !before && !after) {
            itemToInsert = i;
            bool snap;
            surfaceRect.UnionRect(surfaceRect, i->GetBounds(aBuilder, &snap));
          }
        }
      }
    }

    // insert the item into the list if necessary. If the item has a child
    // list, insert that as well
    nsDisplayList* sublist = i->GetSameCoordinateSystemChildren();
    if (itemToInsert || sublist) {
      tmpList.AppendToTop(itemToInsert ? itemToInsert : i);
      // if the item is a list, iterate over it as well
      if (sublist)
        surfaceRect.UnionRect(surfaceRect,
          ClipListToRange(aBuilder, sublist, aRange));
    }
    else {
      // otherwise, just delete the item and don't readd it to the list
      i->~nsDisplayItem();
    }
  }

  // now add all the items back onto the original list again
  aList->AppendToTop(&tmpList);

  return surfaceRect;
}

#ifdef DEBUG
#include <stdio.h>

static bool gDumpRangePaintList = false;
#endif

RangePaintInfo*
PresShell::CreateRangePaintInfo(nsIDOMRange* aRange,
                                nsRect& aSurfaceRect,
                                bool aForPrimarySelection)
{
  RangePaintInfo* info = nullptr;

  nsRange* range = static_cast<nsRange*>(aRange);

  nsIFrame* ancestorFrame;
  nsIFrame* rootFrame = GetRootFrame();

  // If the start or end of the range is the document, just use the root
  // frame, otherwise get the common ancestor of the two endpoints of the
  // range.
  nsINode* startParent = range->GetStartParent();
  nsINode* endParent = range->GetEndParent();
  nsIDocument* doc = startParent->GetCurrentDoc();
  if (startParent == doc || endParent == doc) {
    ancestorFrame = rootFrame;
  }
  else {
    nsINode* ancestor = nsContentUtils::GetCommonAncestor(startParent, endParent);
    NS_ASSERTION(!ancestor || ancestor->IsNodeOfType(nsINode::eCONTENT),
                 "common ancestor is not content");
    if (!ancestor || !ancestor->IsNodeOfType(nsINode::eCONTENT))
      return nullptr;

    nsIContent* ancestorContent = static_cast<nsIContent*>(ancestor);
    ancestorFrame = ancestorContent->GetPrimaryFrame();

    // use the nearest ancestor frame that includes all continuations as the
    // root for building the display list
    while (ancestorFrame &&
           nsLayoutUtils::GetNextContinuationOrSpecialSibling(ancestorFrame))
      ancestorFrame = ancestorFrame->GetParent();
  }

  if (!ancestorFrame)
    return nullptr;

  info = new RangePaintInfo(range, ancestorFrame);

  nsRect ancestorRect = ancestorFrame->GetVisualOverflowRect();

  // get a display list containing the range
  info->mBuilder.SetIncludeAllOutOfFlows();
  if (aForPrimarySelection) {
    info->mBuilder.SetSelectedFramesOnly();
  }
  info->mBuilder.EnterPresShell(ancestorFrame, ancestorRect);
  ancestorFrame->BuildDisplayListForStackingContext(&info->mBuilder,
                                                    ancestorRect, &info->mList);

#ifdef DEBUG
  if (gDumpRangePaintList) {
    fprintf(stderr, "CreateRangePaintInfo --- before ClipListToRange:\n");
    nsFrame::PrintDisplayList(&(info->mBuilder), info->mList);
  }
#endif

  nsRect rangeRect = ClipListToRange(&info->mBuilder, &info->mList, range);

  info->mBuilder.LeavePresShell(ancestorFrame, ancestorRect);

#ifdef DEBUG
  if (gDumpRangePaintList) {
    fprintf(stderr, "CreateRangePaintInfo --- after ClipListToRange:\n");
    nsFrame::PrintDisplayList(&(info->mBuilder), info->mList);
  }
#endif

  // determine the offset of the reference frame for the display list
  // to the root frame. This will allow the coordinates used when painting
  // to all be offset from the same point
  info->mRootOffset = ancestorFrame->GetOffsetTo(rootFrame);
  rangeRect.MoveBy(info->mRootOffset);
  aSurfaceRect.UnionRect(aSurfaceRect, rangeRect);

  return info;
}

already_AddRefed<gfxASurface>
PresShell::PaintRangePaintInfo(nsTArray<nsAutoPtr<RangePaintInfo> >* aItems,
                               nsISelection* aSelection,
                               nsIntRegion* aRegion,
                               nsRect aArea,
                               nsIntPoint& aPoint,
                               nsIntRect* aScreenRect)
{
  nsPresContext* pc = GetPresContext();
  if (!pc || aArea.width == 0 || aArea.height == 0)
    return nullptr;

  nsDeviceContext* deviceContext = pc->DeviceContext();

  // use the rectangle to create the surface
  nsIntRect pixelArea = aArea.ToOutsidePixels(pc->AppUnitsPerDevPixel());

  // if the area of the image is larger than the maximum area, scale it down
  float scale = 0.0;
  nsIntRect rootScreenRect =
    GetRootFrame()->GetScreenRectInAppUnits().ToNearestPixels(
      pc->AppUnitsPerDevPixel());

  // if the image is larger in one or both directions than half the size of
  // the available screen area, scale the image down to that size.
  nsRect maxSize;
  deviceContext->GetClientRect(maxSize);
  nscoord maxWidth = pc->AppUnitsToDevPixels(maxSize.width >> 1);
  nscoord maxHeight = pc->AppUnitsToDevPixels(maxSize.height >> 1);
  bool resize = (pixelArea.width > maxWidth || pixelArea.height > maxHeight);
  if (resize) {
    scale = 1.0;
    // divide the maximum size by the image size in both directions. Whichever
    // direction produces the smallest result determines how much should be
    // scaled.
    if (pixelArea.width > maxWidth)
      scale = NS_MIN(scale, float(maxWidth) / pixelArea.width);
    if (pixelArea.height > maxHeight)
      scale = NS_MIN(scale, float(maxHeight) / pixelArea.height);

    pixelArea.width = NSToIntFloor(float(pixelArea.width) * scale);
    pixelArea.height = NSToIntFloor(float(pixelArea.height) * scale);

    // adjust the screen position based on the rescaled size
    nscoord left = rootScreenRect.x + pixelArea.x;
    nscoord top = rootScreenRect.y + pixelArea.y;
    aScreenRect->x = NSToIntFloor(aPoint.x - float(aPoint.x - left) * scale);
    aScreenRect->y = NSToIntFloor(aPoint.y - float(aPoint.y - top) * scale);
  }
  else {
    // move aScreenRect to the position of the surface in screen coordinates
    aScreenRect->MoveTo(rootScreenRect.x + pixelArea.x, rootScreenRect.y + pixelArea.y);
  }
  aScreenRect->width = pixelArea.width;
  aScreenRect->height = pixelArea.height;

  gfxImageSurface* surface =
    new gfxImageSurface(gfxIntSize(pixelArea.width, pixelArea.height),
                        gfxImageSurface::ImageFormatARGB32);
  if (surface->CairoStatus()) {
    delete surface;
    return nullptr;
  }

  // clear the image
  gfxContext context(surface);
  context.SetOperator(gfxContext::OPERATOR_CLEAR);
  context.Rectangle(gfxRect(0, 0, pixelArea.width, pixelArea.height));
  context.Fill();

  nsRefPtr<nsRenderingContext> rc = new nsRenderingContext();
  rc->Init(deviceContext, surface);

  if (aRegion) {
    // Convert aRegion from CSS pixels to dev pixels
    nsIntRegion region =
      aRegion->ToAppUnits(nsPresContext::AppUnitsPerCSSPixel())
        .ToOutsidePixels(pc->AppUnitsPerDevPixel());
    rc->SetClip(region);
  }

  if (resize)
    rc->Scale(scale, scale);

  // translate so that points are relative to the surface area
  rc->Translate(-aArea.TopLeft());

  // temporarily hide the selection so that text is drawn normally. If a
  // selection is being rendered, use that, otherwise use the presshell's
  // selection.
  nsRefPtr<nsFrameSelection> frameSelection;
  if (aSelection) {
    nsCOMPtr<nsISelectionPrivate> selpriv = do_QueryInterface(aSelection);
    selpriv->GetFrameSelection(getter_AddRefs(frameSelection));
  }
  else {
    frameSelection = FrameSelection();
  }
  int16_t oldDisplaySelection = frameSelection->GetDisplaySelection();
  frameSelection->SetDisplaySelection(nsISelectionController::SELECTION_HIDDEN);

  // next, paint each range in the selection
  int32_t count = aItems->Length();
  for (int32_t i = 0; i < count; i++) {
    RangePaintInfo* rangeInfo = (*aItems)[i];
    // the display lists paint relative to the offset from the reference
    // frame, so translate the rendering context
    nsRenderingContext::AutoPushTranslation
      translate(rc, rangeInfo->mRootOffset);

    aArea.MoveBy(-rangeInfo->mRootOffset.x, -rangeInfo->mRootOffset.y);
    nsRegion visible(aArea);
    rangeInfo->mList.ComputeVisibilityForRoot(&rangeInfo->mBuilder, &visible);
    rangeInfo->mList.PaintRoot(&rangeInfo->mBuilder, rc, nsDisplayList::PAINT_DEFAULT);
    aArea.MoveBy(rangeInfo->mRootOffset.x, rangeInfo->mRootOffset.y);
  }

  // restore the old selection display state
  frameSelection->SetDisplaySelection(oldDisplaySelection);

  NS_ADDREF(surface);
  return surface;
}

already_AddRefed<gfxASurface>
PresShell::RenderNode(nsIDOMNode* aNode,
                      nsIntRegion* aRegion,
                      nsIntPoint& aPoint,
                      nsIntRect* aScreenRect)
{
  // area will hold the size of the surface needed to draw the node, measured
  // from the root frame.
  nsRect area;
  nsTArray<nsAutoPtr<RangePaintInfo> > rangeItems;

  // nothing to draw if the node isn't in a document
  nsCOMPtr<nsINode> node = do_QueryInterface(aNode);
  if (!node->IsInDoc())
    return nullptr;
  
  nsRefPtr<nsRange> range = new nsRange();
  if (NS_FAILED(range->SelectNode(aNode)))
    return nullptr;

  RangePaintInfo* info = CreateRangePaintInfo(range, area, false);
  if (info && !rangeItems.AppendElement(info)) {
    delete info;
    return nullptr;
  }

  if (aRegion) {
    // combine the area with the supplied region
    nsIntRect rrectPixels = aRegion->GetBounds();

    nsRect rrect = rrectPixels.ToAppUnits(nsPresContext::AppUnitsPerCSSPixel());
    area.IntersectRect(area, rrect);
    
    nsPresContext* pc = GetPresContext();
    if (!pc)
      return nullptr;

    // move the region so that it is offset from the topleft corner of the surface
    aRegion->MoveBy(-pc->AppUnitsToDevPixels(area.x),
                    -pc->AppUnitsToDevPixels(area.y));
  }

  return PaintRangePaintInfo(&rangeItems, nullptr, aRegion, area, aPoint,
                             aScreenRect);
}

already_AddRefed<gfxASurface>
PresShell::RenderSelection(nsISelection* aSelection,
                           nsIntPoint& aPoint,
                           nsIntRect* aScreenRect)
{
  // area will hold the size of the surface needed to draw the selection,
  // measured from the root frame.
  nsRect area;
  nsTArray<nsAutoPtr<RangePaintInfo> > rangeItems;

  // iterate over each range and collect them into the rangeItems array.
  // This is done so that the size of selection can be determined so as
  // to allocate a surface area
  int32_t numRanges;
  aSelection->GetRangeCount(&numRanges);
  NS_ASSERTION(numRanges > 0, "RenderSelection called with no selection");

  for (int32_t r = 0; r < numRanges; r++)
  {
    nsCOMPtr<nsIDOMRange> range;
    aSelection->GetRangeAt(r, getter_AddRefs(range));

    RangePaintInfo* info = CreateRangePaintInfo(range, area, true);
    if (info && !rangeItems.AppendElement(info)) {
      delete info;
      return nullptr;
    }
  }

  return PaintRangePaintInfo(&rangeItems, aSelection, nullptr, area, aPoint,
                             aScreenRect);
}

nsresult
PresShell::AddPrintPreviewBackgroundItem(nsDisplayListBuilder& aBuilder,
                                         nsDisplayList&        aList,
                                         nsIFrame*             aFrame,
                                         const nsRect&         aBounds)
{
  return aList.AppendNewToBottom(new (&aBuilder)
    nsDisplaySolidColor(&aBuilder, aFrame, aBounds, NS_RGB(115, 115, 115)));
}

static bool
AddCanvasBackgroundColor(const nsDisplayList& aList, nsIFrame* aCanvasFrame,
                         nscolor aColor)
{
  for (nsDisplayItem* i = aList.GetBottom(); i; i = i->GetAbove()) {
    if (i->GetUnderlyingFrame() == aCanvasFrame &&
        i->GetType() == nsDisplayItem::TYPE_CANVAS_BACKGROUND) {
      nsDisplayCanvasBackground* bg = static_cast<nsDisplayCanvasBackground*>(i);
      bg->SetExtraBackgroundColor(aColor);
      return true;
    }
    nsDisplayList* sublist = i->GetSameCoordinateSystemChildren();
    if (sublist && AddCanvasBackgroundColor(*sublist, aCanvasFrame, aColor))
      return true;
  }
  return false;
}

nsresult PresShell::AddCanvasBackgroundColorItem(nsDisplayListBuilder& aBuilder,
                                                 nsDisplayList&        aList,
                                                 nsIFrame*             aFrame,
                                                 const nsRect&         aBounds,
                                                 nscolor               aBackstopColor,
                                                 uint32_t              aFlags)
{
  if (aBounds.IsEmpty()) {
    return NS_OK;
  }
  // We don't want to add an item for the canvas background color if the frame
  // (sub)tree we are painting doesn't include any canvas frames. There isn't
  // an easy way to check this directly, but if we check if the root of the
  // (sub)tree we are painting is a canvas frame that should cover us in all
  // cases (it will usually be a viewport frame when we have a canvas frame in
  // the (sub)tree).
  if (!(aFlags & nsIPresShell::FORCE_DRAW) &&
      !nsCSSRendering::IsCanvasFrame(aFrame)) {
    return NS_OK;
  }

  nscolor bgcolor = NS_ComposeColors(aBackstopColor, mCanvasBackgroundColor);
  if (NS_GET_A(bgcolor) == 0)
    return NS_OK;

  // To make layers work better, we want to avoid having a big non-scrolled 
  // color background behind a scrolled transparent background. Instead,
  // we'll try to move the color background into the scrolled content
  // by making nsDisplayCanvasBackground paint it.
  if (!aFrame->GetParent()) {
    nsIScrollableFrame* sf =
      aFrame->PresContext()->PresShell()->GetRootScrollFrameAsScrollable();
    if (sf) {
      nsCanvasFrame* canvasFrame = do_QueryFrame(sf->GetScrolledFrame());
      if (canvasFrame && canvasFrame->IsVisibleForPainting(&aBuilder)) {
        if (AddCanvasBackgroundColor(aList, canvasFrame, bgcolor))
          return NS_OK;
      }
    }
  }

  return aList.AppendNewToBottom(
      new (&aBuilder) nsDisplaySolidColor(&aBuilder, aFrame, aBounds, bgcolor));
}

static bool IsTransparentContainerElement(nsPresContext* aPresContext)
{
  nsCOMPtr<nsISupports> container = aPresContext->GetContainerInternal();
  nsCOMPtr<nsIDocShellTreeItem> docShellItem = do_QueryInterface(container);
  nsCOMPtr<nsPIDOMWindow> pwin(do_GetInterface(docShellItem));
  if (!pwin)
    return false;
  nsCOMPtr<nsIContent> containerElement =
    do_QueryInterface(pwin->GetFrameElementInternal());
  return containerElement &&
         containerElement->HasAttr(kNameSpaceID_None, nsGkAtoms::transparent);
}

nscolor PresShell::GetDefaultBackgroundColorToDraw()
{
  if (!mPresContext || !mPresContext->GetBackgroundColorDraw()) {
    return NS_RGB(255,255,255);
  }
  return mPresContext->DefaultBackgroundColor();
}

void PresShell::UpdateCanvasBackground()
{
  // If we have a frame tree and it has style information that
  // specifies the background color of the canvas, update our local
  // cache of that color.
  nsIFrame* rootStyleFrame = FrameConstructor()->GetRootElementStyleFrame();
  if (rootStyleFrame) {
    nsStyleContext* bgStyle =
      nsCSSRendering::FindRootFrameBackground(rootStyleFrame);
    // XXX We should really be passing the canvasframe, not the root element
    // style frame but we don't have access to the canvasframe here. It isn't
    // a problem because only a few frames can return something other than true
    // and none of them would be a canvas frame or root element style frame.
    bool drawBackgroundImage;
    bool drawBackgroundColor;

    mCanvasBackgroundColor =
      nsCSSRendering::DetermineBackgroundColor(mPresContext, bgStyle,
                                               rootStyleFrame,
                                               drawBackgroundImage,
                                               drawBackgroundColor);
    if (GetPresContext()->IsCrossProcessRootContentDocument() &&
        !IsTransparentContainerElement(mPresContext)) {
      mCanvasBackgroundColor =
        NS_ComposeColors(GetDefaultBackgroundColorToDraw(), mCanvasBackgroundColor);
    }
  }

  // If the root element of the document (ie html) has style 'display: none'
  // then the document's background color does not get drawn; cache the
  // color we actually draw.
  if (!FrameConstructor()->GetRootElementFrame()) {
    mCanvasBackgroundColor = GetDefaultBackgroundColorToDraw();
  }
  if (XRE_GetProcessType() == GeckoProcessType_Content) {
    if (TabChild* tabChild = GetTabChildFrom(this)) {
      tabChild->SetBackgroundColor(mCanvasBackgroundColor);
    }
  }
}

nscolor PresShell::ComputeBackstopColor(nsIView* aDisplayRoot)
{
  nsIWidget* widget = aDisplayRoot->GetWidget();
  if (widget && (widget->GetTransparencyMode() != eTransparencyOpaque ||
                 widget->WidgetPaintsBackground())) {
    // Within a transparent widget, so the backstop color must be
    // totally transparent.
    return NS_RGBA(0,0,0,0);
  }
  // Within an opaque widget (or no widget at all), so the backstop
  // color must be totally opaque. The user's default background
  // as reported by the prescontext is guaranteed to be opaque.
  return GetDefaultBackgroundColorToDraw();
}

struct PaintParams {
  nscolor mBackgroundColor;
};

LayerManager* PresShell::GetLayerManager()
{
  NS_ASSERTION(mViewManager, "Should have view manager");

  nsIView* rootView = mViewManager->GetRootView();
  if (rootView) {
    if (nsIWidget* widget = rootView->GetWidget()) {
      return widget->GetLayerManager();
    }
  }
  return nullptr;
}

void PresShell::SetIgnoreViewportScrolling(bool aIgnore)
{
  if (IgnoringViewportScrolling() == aIgnore) {
    return;
  }
  RenderingState state(this);
  state.mRenderFlags = ChangeFlag(state.mRenderFlags, aIgnore,
                                  STATE_IGNORING_VIEWPORT_SCROLLING);
  SetRenderingState(state);
}

void PresShell::SetDisplayPort(const nsRect& aDisplayPort)
{
  NS_ABORT_IF_FALSE(false, "SetDisplayPort is deprecated");
}

nsresult PresShell::SetResolution(float aXResolution, float aYResolution)
{
  if (!(aXResolution > 0.0 && aYResolution > 0.0)) {
    return NS_ERROR_ILLEGAL_VALUE;
  }
  if (aXResolution == mXResolution && aYResolution == mYResolution) {
    return NS_OK;
  }
  RenderingState state(this);
  state.mXResolution = aXResolution;
  state.mYResolution = aYResolution;
  SetRenderingState(state);
  return NS_OK;
 }

void PresShell::SetRenderingState(const RenderingState& aState)
{
  if (mRenderFlags != aState.mRenderFlags) {
    // Rendering state changed in a way that forces us to flush any
    // retained layers we might already have.
    LayerManager* manager = GetLayerManager();
    if (manager) {
      FrameLayerBuilder::InvalidateAllLayers(manager);
    }
  }

  mRenderFlags = aState.mRenderFlags;
  mXResolution = aState.mXResolution;
  mYResolution = aState.mYResolution;
}

void PresShell::SynthesizeMouseMove(bool aFromScroll)
{
  if (!sSynthMouseMove)
    return;

  if (mPaintingSuppressed || !mIsActive || !mPresContext) {
    return;
  }

  if (!mPresContext->IsRoot()) {
    nsIPresShell* rootPresShell = GetRootPresShell();
    if (rootPresShell) {
      rootPresShell->SynthesizeMouseMove(aFromScroll);
    }
    return;
  }

  if (mMouseLocation == nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE))
    return;

  if (!mSynthMouseMoveEvent.IsPending()) {
    nsRefPtr<nsSynthMouseMoveEvent> ev =
        new nsSynthMouseMoveEvent(this, aFromScroll);

    if (!GetPresContext()->RefreshDriver()->AddRefreshObserver(ev,
                                                               Flush_Display)) {
      NS_WARNING("failed to dispatch nsSynthMouseMoveEvent");
      return;
    }

    mSynthMouseMoveEvent = ev;
  }
}

/**
 * Find the first floating view with a widget in a postorder traversal of the
 * view tree that contains the point. Thus more deeply nested floating views
 * are preferred over their ancestors, and floating views earlier in the
 * view hierarchy (i.e., added later) are preferred over their siblings.
 * This is adequate for finding the "topmost" floating view under a point,
 * given that floating views don't supporting having a specific z-index.
 * 
 * We cannot exit early when aPt is outside the view bounds, because floating
 * views aren't necessarily included in their parent's bounds, so this could
 * traverse the entire view hierarchy --- use carefully.
 */
static nsIView* FindFloatingViewContaining(nsIView* aView, nsPoint aPt)
{
  if (aView->GetVisibility() == nsViewVisibility_kHide)
    // No need to look into descendants.
    return nullptr;

  nsIFrame* frame = aView->GetFrame();
  if (frame) {
    if (!frame->IsVisibleConsideringAncestors(nsIFrame::VISIBILITY_CROSS_CHROME_CONTENT_BOUNDARY) ||
        !frame->PresContext()->PresShell()->IsActive()) {
      return nullptr;
    }
  }

  for (nsIView* v = aView->GetFirstChild(); v; v = v->GetNextSibling()) {
    nsIView* r = FindFloatingViewContaining(v, v->ConvertFromParentCoords(aPt));
    if (r)
      return r;
  }

  if (aView->GetFloating() && aView->HasWidget() &&
      aView->GetDimensions().Contains(aPt))
    return aView;
    
  return nullptr;
}

/*
 * This finds the first view containing the given point in a postorder
 * traversal of the view tree that contains the point, assuming that the
 * point is not in a floating view.  It assumes that only floating views
 * extend outside the bounds of their parents.
 *
 * This methods should only be called if FindFloatingViewContaining
 * returns null.
 */
static nsIView* FindViewContaining(nsIView* aView, nsPoint aPt)
{
  if (!aView->GetDimensions().Contains(aPt) ||
      aView->GetVisibility() == nsViewVisibility_kHide) {
    return nullptr;
  }

  nsIFrame* frame = aView->GetFrame();
  if (frame) {
    if (!frame->IsVisibleConsideringAncestors(nsIFrame::VISIBILITY_CROSS_CHROME_CONTENT_BOUNDARY) ||
        !frame->PresContext()->PresShell()->IsActive()) {
      return nullptr;
    }
  }

  for (nsIView* v = aView->GetFirstChild(); v; v = v->GetNextSibling()) {
    nsIView* r = FindViewContaining(v, v->ConvertFromParentCoords(aPt));
    if (r)
      return r;
  }

  return aView;
}

void
PresShell::ProcessSynthMouseMoveEvent(bool aFromScroll)
{
  // If drag session has started, we shouldn't synthesize mousemove event.
  nsCOMPtr<nsIDragSession> dragSession = nsContentUtils::GetDragSession();
  if (dragSession) {
    mSynthMouseMoveEvent.Forget();
    return;
  }

  // allow new event to be posted while handling this one only if the
  // source of the event is a scroll (to prevent infinite reflow loops)
  if (aFromScroll) {
    mSynthMouseMoveEvent.Forget();
  }

  nsIView* rootView = mViewManager ? mViewManager->GetRootView() : nullptr;
  if (mMouseLocation == nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE) ||
      !rootView || !rootView->HasWidget() || !mPresContext) {
    mSynthMouseMoveEvent.Forget();
    return;
  }

  NS_ASSERTION(mPresContext->IsRoot(), "Only a root pres shell should be here");

  // Hold a ref to ourselves so DispatchEvent won't destroy us (since
  // we need to access members after we call DispatchEvent).
  nsCOMPtr<nsIPresShell> kungFuDeathGrip(this);
  
#ifdef DEBUG_MOUSE_LOCATION
  printf("[ps=%p]synthesizing mouse move to (%d,%d)\n",
         this, mMouseLocation.x, mMouseLocation.y);
#endif

  int32_t APD = mPresContext->AppUnitsPerDevPixel();

  // We need a widget to put in the event we are going to dispatch so we look
  // for a view that has a widget and the mouse location is over. We first look
  // for floating views, if there isn't one we use the root view. |view| holds
  // that view.
  nsIView* view = nullptr;

  // The appunits per devpixel ratio of |view|.
  int32_t viewAPD;

  // refPoint will be mMouseLocation relative to the widget of |view|, the
  // widget we will put in the event we dispatch, in viewAPD appunits
  nsPoint refpoint(0, 0);

  // We always dispatch the event to the pres shell that contains the view that
  // the mouse is over. pointVM is the VM of that pres shell.
  nsIViewManager *pointVM = nullptr;

  // This could be a bit slow (traverses entire view hierarchy)
  // but it's OK to do it once per synthetic mouse event
  view = FindFloatingViewContaining(rootView, mMouseLocation);
  if (!view) {
    view = rootView;
    nsIView *pointView = FindViewContaining(rootView, mMouseLocation);
    // pointView can be null in situations related to mouse capture
    pointVM = (pointView ? pointView : view)->GetViewManager();
    refpoint = mMouseLocation + rootView->ViewToWidgetOffset();
    viewAPD = APD;
  } else {
    pointVM = view->GetViewManager();
    nsIFrame* frame = view->GetFrame();
    NS_ASSERTION(frame, "floating views can't be anonymous");
    viewAPD = frame->PresContext()->AppUnitsPerDevPixel();
    refpoint = mMouseLocation.ConvertAppUnits(APD, viewAPD);
    refpoint -= view->GetOffsetTo(rootView);
    refpoint += view->ViewToWidgetOffset();
  }
  NS_ASSERTION(view->GetWidget(), "view should have a widget here");
  nsMouseEvent event(true, NS_MOUSE_MOVE, view->GetWidget(),
                     nsMouseEvent::eSynthesized);
  event.refPoint = refpoint.ToNearestPixels(viewAPD);
  event.time = PR_IntervalNow();
  // XXX set event.modifiers ?
  // XXX mnakano I think that we should get the latest information from widget.

  nsCOMPtr<nsIPresShell> shell = pointVM->GetPresShell();
  if (shell) {
    shell->DispatchSynthMouseMove(&event, !aFromScroll);
  }

  if (!aFromScroll) {
    mSynthMouseMoveEvent.Forget();
  }
}

class nsAutoNotifyDidPaint
{
public:
  nsAutoNotifyDidPaint(PresShell* aShell, uint32_t aFlags)
    : mShell(aShell), mFlags(aFlags)
  {
  }
  ~nsAutoNotifyDidPaint()
  {
    mShell->GetPresContext()->NotifyDidPaintForSubtree(mFlags);
    if (!(mFlags & nsIPresShell::PAINT_WILL_SEND_DID_PAINT) &&
        nsContentUtils::XPConnect()) {
      nsContentUtils::XPConnect()->NotifyDidPaint();
    }
  }

private:
  PresShell* mShell;
  uint32_t mFlags;
};

void
PresShell::Paint(nsIView*        aViewToPaint,
                 const nsRegion& aDirtyRegion,
                 uint32_t        aFlags)
{
  SAMPLE_LABEL("Paint", "PresShell::Paint");
  NS_ASSERTION(!mIsDestroying, "painting a destroyed PresShell");
  NS_ASSERTION(aViewToPaint, "null view");

  nsAutoNotifyDidPaint notifyDidPaint(this, aFlags);

  nsPresContext* presContext = GetPresContext();
  AUTO_LAYOUT_PHASE_ENTRY_POINT(presContext, Paint);

  nsIFrame* frame = aViewToPaint->GetFrame();

  bool isRetainingManager;
  LayerManager* layerManager =
    aViewToPaint->GetWidget()->GetLayerManager(&isRetainingManager);
  NS_ASSERTION(layerManager, "Must be in paint event");

  if (mIsFirstPaint) {
    layerManager->SetIsFirstPaint();
    mIsFirstPaint = false;
  }

  if (frame && isRetainingManager) {
    // Try to do an empty transaction, if the frame tree does not
    // need to be updated. Do not try to do an empty transaction on
    // a non-retained layer manager (like the BasicLayerManager that
    // draws the window title bar on Mac), because a) it won't work
    // and b) below we don't want to clear NS_FRAME_UPDATE_LAYER_TREE,
    // that will cause us to forget to update the real layer manager!
    if (!(aFlags & PAINT_LAYERS)) {
      if (layerManager->HasShadowManager()) {
        return;
      }
      layerManager->BeginTransaction();
      if (layerManager->EndEmptyTransaction()) {
        return;
      }
      NS_WARNING("Must complete empty transaction when compositing!");
    } else {
      layerManager->BeginTransaction();
    }

    if (!(frame->GetStateBits() & NS_FRAME_UPDATE_LAYER_TREE)) {
      NotifySubDocInvalidationFunc computeInvalidFunc =
        presContext->MayHavePaintEventListenerInSubDocument() ? nsPresContext::NotifySubDocInvalidation : 0;
      bool computeInvalidRect = computeInvalidFunc ||
                                (layerManager->GetBackendType() == LAYERS_BASIC);

      nsAutoPtr<LayerProperties> props(computeInvalidRect ? 
                                         LayerProperties::CloneFrom(layerManager->GetRoot()) : 
                                         nullptr);

      if (layerManager->EndEmptyTransaction((aFlags & PAINT_COMPOSITE) ?
            LayerManager::END_DEFAULT : LayerManager::END_NO_COMPOSITE)) {
        nsIntRect invalid;
        if (props) {
          invalid = props->ComputeDifferences(layerManager->GetRoot(), computeInvalidFunc);
        } else {
          LayerProperties::ClearInvalidations(layerManager->GetRoot());
        }
        if (props) {
          if (!invalid.IsEmpty()) {
            nsRect rect(presContext->DevPixelsToAppUnits(invalid.x),
                        presContext->DevPixelsToAppUnits(invalid.y),
                        presContext->DevPixelsToAppUnits(invalid.width),
                        presContext->DevPixelsToAppUnits(invalid.height));
            aViewToPaint->GetViewManager()->InvalidateViewNoSuppression(aViewToPaint, rect);
            presContext->NotifyInvalidation(invalid, 0);
          }
        } else {
          aViewToPaint->GetViewManager()->InvalidateView(aViewToPaint);
        }

        frame->UpdatePaintCountForPaintedPresShells();
        return;
      }
    }
    frame->RemoveStateBits(NS_FRAME_UPDATE_LAYER_TREE);
  } else {
    layerManager->BeginTransaction();
  }
  if (frame) {
    frame->ClearPresShellsFromLastPaint();
  }

  nscolor bgcolor = ComputeBackstopColor(aViewToPaint);
  uint32_t flags = nsLayoutUtils::PAINT_WIDGET_LAYERS | nsLayoutUtils::PAINT_EXISTING_TRANSACTION;
  if (!(aFlags & PAINT_COMPOSITE)) {
    flags |= nsLayoutUtils::PAINT_NO_COMPOSITE;
  }

  if (frame) {
    // Defer invalidates that are triggered during painting, and discard
    // invalidates of areas that are already being repainted.
    // The layer system can trigger invalidates during painting
    // (see FrameLayerBuilder).
    frame->BeginDeferringInvalidatesForDisplayRoot(aDirtyRegion);

    // We can paint directly into the widget using its layer manager.
    nsLayoutUtils::PaintFrame(nullptr, frame, aDirtyRegion, bgcolor, flags);

    frame->EndDeferringInvalidatesForDisplayRoot();
    return;
  }

  nsRefPtr<ColorLayer> root = layerManager->CreateColorLayer();
  if (root) {
    nsPresContext* pc = GetPresContext();
    nsIntRect bounds =
      pc->GetVisibleArea().ToOutsidePixels(pc->AppUnitsPerDevPixel());
    bgcolor = NS_ComposeColors(bgcolor, mCanvasBackgroundColor);
    root->SetColor(bgcolor);
    root->SetVisibleRegion(bounds);
    layerManager->SetRoot(root);
  }
  layerManager->EndTransaction(NULL, NULL, (aFlags & PAINT_COMPOSITE) ?
    LayerManager::END_DEFAULT : LayerManager::END_NO_COMPOSITE);
}

// static
void
nsIPresShell::SetCapturingContent(nsIContent* aContent, uint8_t aFlags)
{
  // If capture was set for pointer lock, don't unlock unless we are coming
  // out of pointer lock explicitly.
  if (!aContent && gCaptureInfo.mPointerLock &&
      !(aFlags & CAPTURE_POINTERLOCK)) {
    return;
  }

  NS_IF_RELEASE(gCaptureInfo.mContent);

  // only set capturing content if allowed or the CAPTURE_IGNOREALLOWED or
  // CAPTURE_POINTERLOCK flags are used.
  if ((aFlags & CAPTURE_IGNOREALLOWED) || gCaptureInfo.mAllowed ||
      (aFlags & CAPTURE_POINTERLOCK)) {
    if (aContent) {
      NS_ADDREF(gCaptureInfo.mContent = aContent);
    }
    // CAPTURE_POINTERLOCK is the same as CAPTURE_RETARGETTOELEMENT & CAPTURE_IGNOREALLOWED
    gCaptureInfo.mRetargetToElement = ((aFlags & CAPTURE_RETARGETTOELEMENT) != 0) ||
                                      ((aFlags & CAPTURE_POINTERLOCK) != 0);
    gCaptureInfo.mPreventDrag = (aFlags & CAPTURE_PREVENTDRAG) != 0;
    gCaptureInfo.mPointerLock = (aFlags & CAPTURE_POINTERLOCK) != 0;
  }
}

nsIFrame*
PresShell::GetCurrentEventFrame()
{
  if (MOZ_UNLIKELY(mIsDestroying)) {
    return nullptr;
  }
    
  if (!mCurrentEventFrame && mCurrentEventContent) {
    // Make sure the content still has a document reference. If not,
    // then we assume it is no longer in the content tree and the
    // frame shouldn't get an event, nor should we even assume its
    // safe to try and find the frame.
    if (mCurrentEventContent->GetDocument()) {
      mCurrentEventFrame = mCurrentEventContent->GetPrimaryFrame();
    }
  }

  return mCurrentEventFrame;
}

nsIFrame*
PresShell::GetEventTargetFrame()
{
  return GetCurrentEventFrame();
}

already_AddRefed<nsIContent>
PresShell::GetEventTargetContent(nsEvent* aEvent)
{
  nsIContent* content = nullptr;

  if (mCurrentEventContent) {
    content = mCurrentEventContent;
    NS_IF_ADDREF(content);
  } else {
    nsIFrame* currentEventFrame = GetCurrentEventFrame();
    if (currentEventFrame) {
      currentEventFrame->GetContentForEvent(aEvent, &content);
    } else {
      content = nullptr;
    }
  }
  return content;
}

void
PresShell::PushCurrentEventInfo(nsIFrame* aFrame, nsIContent* aContent)
{
  if (mCurrentEventFrame || mCurrentEventContent) {
    mCurrentEventFrameStack.InsertElementAt(0, mCurrentEventFrame);
    mCurrentEventContentStack.InsertObjectAt(mCurrentEventContent, 0);
  }
  mCurrentEventFrame = aFrame;
  mCurrentEventContent = aContent;
}

void
PresShell::PopCurrentEventInfo()
{
  mCurrentEventFrame = nullptr;
  mCurrentEventContent = nullptr;

  if (0 != mCurrentEventFrameStack.Length()) {
    mCurrentEventFrame = mCurrentEventFrameStack.ElementAt(0);
    mCurrentEventFrameStack.RemoveElementAt(0);
    mCurrentEventContent = mCurrentEventContentStack.ObjectAt(0);
    mCurrentEventContentStack.RemoveObjectAt(0);
  }
}

bool PresShell::InZombieDocument(nsIContent *aContent)
{
  // If a content node points to a null document, or the document is not
  // attached to a window, then it is possibly in a zombie document,
  // about to be replaced by a newly loading document.
  // Such documents cannot handle DOM events.
  // It might actually be in a node not attached to any document,
  // in which case there is not parent presshell to retarget it to.
  nsIDocument *doc = aContent->GetDocument();
  return !doc || !doc->GetWindow();
}

already_AddRefed<nsPIDOMWindow>
PresShell::GetRootWindow()
{
  nsCOMPtr<nsPIDOMWindow> window =
    do_QueryInterface(mDocument->GetWindow());
  if (window) {
    nsCOMPtr<nsPIDOMWindow> rootWindow = window->GetPrivateRoot();
    NS_ASSERTION(rootWindow, "nsPIDOMWindow::GetPrivateRoot() returns NULL");
    return rootWindow.forget();
  }

  // If we don't have DOM window, we're zombie, we should find the root window
  // with our parent shell.
  nsCOMPtr<nsIPresShell> parent = GetParentPresShell();
  NS_ENSURE_TRUE(parent, nullptr);
  return parent->GetRootWindow();
}

already_AddRefed<nsIPresShell>
PresShell::GetParentPresShell()
{
  NS_ENSURE_TRUE(mPresContext, nullptr);
  nsCOMPtr<nsISupports> container = mPresContext->GetContainer();
  if (!container) {
    container = do_QueryReferent(mForwardingContainer);
  }

  // Now, find the parent pres shell and send the event there
  nsCOMPtr<nsIDocShellTreeItem> treeItem = do_QueryInterface(container);
  // Might have gone away, or never been around to start with
  NS_ENSURE_TRUE(treeItem, nullptr);

  nsCOMPtr<nsIDocShellTreeItem> parentTreeItem;
  treeItem->GetParent(getter_AddRefs(parentTreeItem));
  nsCOMPtr<nsIDocShell> parentDocShell = do_QueryInterface(parentTreeItem);
  NS_ENSURE_TRUE(parentDocShell && treeItem != parentTreeItem, nullptr);

  nsIPresShell* parentPresShell = nullptr;
  parentDocShell->GetPresShell(&parentPresShell);
  return parentPresShell;
}

nsresult
PresShell::RetargetEventToParent(nsGUIEvent*     aEvent,
                                 nsEventStatus*  aEventStatus)
{
  // Send this events straight up to the parent pres shell.
  // We do this for keystroke events in zombie documents or if either a frame
  // or a root content is not present.
  // That way at least the UI key bindings can work.

  nsCOMPtr<nsIPresShell> kungFuDeathGrip(this);
  nsCOMPtr<nsIPresShell> parentPresShell = GetParentPresShell();
  NS_ENSURE_TRUE(parentPresShell, NS_ERROR_FAILURE);

  // Fake the event as though it's from the parent pres shell's root frame.
  return parentPresShell->HandleEvent(parentPresShell->GetRootFrame(), aEvent, true, aEventStatus);
}

void
PresShell::DisableNonTestMouseEvents(bool aDisable)
{
  sDisableNonTestMouseEvents = aDisable;
}

already_AddRefed<nsPIDOMWindow>
PresShell::GetFocusedDOMWindowInOurWindow()
{
  nsCOMPtr<nsPIDOMWindow> rootWindow = GetRootWindow();
  NS_ENSURE_TRUE(rootWindow, nullptr);
  nsPIDOMWindow* focusedWindow;
  nsFocusManager::GetFocusedDescendant(rootWindow, true, &focusedWindow);
  return focusedWindow;
}

void
PresShell::RecordMouseLocation(nsGUIEvent* aEvent)
{
  if (!mPresContext)
    return;

  if (!mPresContext->IsRoot()) {
    PresShell* rootPresShell = GetRootPresShell();
    if (rootPresShell) {
      rootPresShell->RecordMouseLocation(aEvent);
    }
    return;
  }

  if ((aEvent->message == NS_MOUSE_MOVE &&
       static_cast<nsMouseEvent*>(aEvent)->reason == nsMouseEvent::eReal) ||
      aEvent->message == NS_MOUSE_ENTER ||
      aEvent->message == NS_MOUSE_BUTTON_DOWN ||
      aEvent->message == NS_MOUSE_BUTTON_UP) {
    nsIFrame* rootFrame = GetRootFrame();
    if (!rootFrame) {
      nsIView* rootView = mViewManager->GetRootView();
      mMouseLocation = nsLayoutUtils::TranslateWidgetToView(mPresContext,
        aEvent->widget, aEvent->refPoint, rootView);
    } else {
      mMouseLocation =
        nsLayoutUtils::GetEventCoordinatesRelativeTo(aEvent, rootFrame);
    }
#ifdef DEBUG_MOUSE_LOCATION
    if (aEvent->message == NS_MOUSE_ENTER)
      printf("[ps=%p]got mouse enter for %p\n",
             this, aEvent->widget);
    printf("[ps=%p]setting mouse location to (%d,%d)\n",
           this, mMouseLocation.x, mMouseLocation.y);
#endif
    if (aEvent->message == NS_MOUSE_ENTER)
      SynthesizeMouseMove(false);
  } else if (aEvent->message == NS_MOUSE_EXIT) {
    // Although we only care about the mouse moving into an area for which this
    // pres shell doesn't receive mouse move events, we don't check which widget
    // the mouse exit was for since this seems to vary by platform.  Hopefully
    // this won't matter at all since we'll get the mouse move or enter after
    // the mouse exit when the mouse moves from one of our widgets into another.
    mMouseLocation = nsPoint(NS_UNCONSTRAINEDSIZE, NS_UNCONSTRAINEDSIZE);
#ifdef DEBUG_MOUSE_LOCATION
    printf("[ps=%p]got mouse exit for %p\n",
           this, aEvent->widget);
    printf("[ps=%p]clearing mouse location\n",
           this);
#endif
  }
}

static void
EvictTouchPoint(nsCOMPtr<nsIDOMTouch>& aTouch)
{
  nsIWidget *widget = nullptr;
  // is there an easier/better way to dig out the widget?
  nsCOMPtr<nsINode> node(do_QueryInterface(aTouch->GetTarget()));
  if (!node) {
    return;
  }
  nsIDocument* doc = node->GetCurrentDoc();
  if (!doc) {
    return;
  }
  nsIPresShell *presShell = doc->GetShell();
  if (!presShell) {
    return;
  }
  nsIFrame* frame = presShell->GetRootFrame();
  if (!frame) {
    return;
  }
  nsPoint pt(aTouch->mRefPoint.x, aTouch->mRefPoint.y);
  widget = frame->GetView()->GetNearestWidget(&pt);

  if (!widget) {
    return;
  }
  
  nsTouchEvent event(true, NS_TOUCH_END, widget);
  event.widget = widget;
  event.time = PR_IntervalNow();
  event.touches.AppendElement(aTouch);

  nsEventStatus status;
  widget->DispatchEvent(&event, status);
}

static PLDHashOperator
AppendToTouchList(const uint32_t& aKey, nsCOMPtr<nsIDOMTouch>& aData, void *aTouchList)
{
  nsTArray<nsCOMPtr<nsIDOMTouch> > *touches = static_cast<nsTArray<nsCOMPtr<nsIDOMTouch> > *>(aTouchList);
  aData->mChanged = false;
  touches->AppendElement(aData);
  return PL_DHASH_NEXT;
}

static PLDHashOperator
FindAnyTarget(const uint32_t& aKey, nsCOMPtr<nsIDOMTouch>& aData,
              void* aAnyTarget)
{
  if (aData) {
    nsCOMPtr<nsIDOMEventTarget> target;
    aData->GetTarget(getter_AddRefs(target));
    if (target) {
      nsCOMPtr<nsIContent>* content =
        static_cast<nsCOMPtr<nsIContent>*>(aAnyTarget);
      *content = do_QueryInterface(target);
      return PL_DHASH_STOP;
    }
  }
  return PL_DHASH_NEXT;
}

nsIFrame* GetNearestFrameContainingPresShell(nsIPresShell* aPresShell)
{
  nsIView* view = aPresShell->GetViewManager()->GetRootView();
  while (view && !view->GetFrame()) {
    view = view->GetParent();
  }

  nsIFrame* frame = nullptr;
  if (view) {
    frame = view->GetFrame();
  }

  return frame;
}

nsresult
PresShell::HandleEvent(nsIFrame        *aFrame,
                       nsGUIEvent*     aEvent,
                       bool            aDontRetargetEvents,
                       nsEventStatus*  aEventStatus)
{
  NS_ASSERTION(aFrame, "null frame");

  if (mIsDestroying ||
      (sDisableNonTestMouseEvents && NS_IS_MOUSE_EVENT(aEvent) &&
       !(aEvent->flags & NS_EVENT_FLAG_SYNTHETIC_TEST_EVENT))) {
    return NS_OK;
  }

  RecordMouseLocation(aEvent);

  if (!nsContentUtils::IsSafeToRunScript())
    return NS_OK;

  nsIContent* capturingContent =
    NS_IS_MOUSE_EVENT(aEvent) || aEvent->eventStructType == NS_WHEEL_EVENT ?
      GetCapturingContent() : nullptr;

  nsCOMPtr<nsIDocument> retargetEventDoc;
  if (!aDontRetargetEvents) {
    // key and IME related events should not cross top level window boundary.
    // Basically, such input events should be fired only on focused widget.
    // However, some IMEs might need to clean up composition after focused
    // window is deactivated.  And also some tests on MozMill want to test key
    // handling on deactivated window because MozMill window can be activated
    // during tests.  So, there is no merit the events should be redirected to
    // active window.  So, the events should be handled on the last focused
    // content in the last focused DOM window in same top level window.
    // Note, if no DOM window has been focused yet, we can discard the events.
    if (NS_IsEventTargetedAtFocusedWindow(aEvent)) {
      nsCOMPtr<nsPIDOMWindow> window = GetFocusedDOMWindowInOurWindow();
      // No DOM window in same top level window has not been focused yet,
      // discard the events.
      if (!window) {
        return NS_OK;
      }

      retargetEventDoc = do_QueryInterface(window->GetExtantDocument());
      if (!retargetEventDoc)
        return NS_OK;
    } else if (capturingContent) {
      // if the mouse is being captured then retarget the mouse event at the
      // document that is being captured.
      retargetEventDoc = capturingContent->GetCurrentDoc();
#ifdef ANDROID
    } else if (aEvent->eventStructType == NS_TOUCH_EVENT) {
      retargetEventDoc = GetTouchEventTargetDocument();
#endif
    }

    if (retargetEventDoc) {
      nsCOMPtr<nsIPresShell> presShell = retargetEventDoc->GetShell();
      if (!presShell)
        return NS_OK;

      if (presShell != this) {
        nsIFrame* frame = presShell->GetRootFrame();
        if (!frame) {
          if (aEvent->message == NS_QUERY_TEXT_CONTENT ||
              NS_IS_CONTENT_COMMAND_EVENT(aEvent)) {
            return NS_OK;
          }

          frame = GetNearestFrameContainingPresShell(presShell);
        }

        if (!frame)
          return NS_OK;

        nsCOMPtr<nsIPresShell> shell = frame->PresContext()->GetPresShell();
        return shell->HandleEvent(frame, aEvent, true, aEventStatus);
      }
    }
  }

  if (aEvent->eventStructType == NS_KEY_EVENT &&
      mDocument && mDocument->EventHandlingSuppressed()) {
    if (aEvent->message == NS_KEY_DOWN) {
      mNoDelayedKeyEvents = true;
    } else if (!mNoDelayedKeyEvents) {
      nsDelayedEvent* event =
        new nsDelayedKeyEvent(static_cast<nsKeyEvent*>(aEvent));
      if (!mDelayedEvents.AppendElement(event)) {
        delete event;
      }
    }
    return NS_OK;
  }

  nsIFrame* frame = aFrame;

  if (aEvent->eventStructType == NS_TOUCH_EVENT) {
    FlushPendingNotifications(Flush_Layout);
    frame = GetNearestFrameContainingPresShell(this);
  }

  bool dispatchUsingCoordinates = NS_IsEventUsingCoordinates(aEvent);
  if (dispatchUsingCoordinates) {
    NS_WARN_IF_FALSE(frame, "Nothing to handle this event!");
    if (!frame)
      return NS_OK;

    nsPresContext* framePresContext = frame->PresContext();
    nsPresContext* rootPresContext = framePresContext->GetRootPresContext();
    NS_ASSERTION(rootPresContext == mPresContext->GetRootPresContext(),
                 "How did we end up outside the connected prescontext/viewmanager hierarchy?"); 
    // If we aren't starting our event dispatch from the root frame of the root prescontext,
    // then someone must be capturing the mouse. In that case we don't want to search the popup
    // list.
    if (framePresContext == rootPresContext &&
        frame == mFrameConstructor->GetRootFrame()) {
      nsIFrame* popupFrame =
        nsLayoutUtils::GetPopupFrameForEventCoordinates(rootPresContext, aEvent);
      // If the popupFrame is an ancestor of the 'frame', the frame should
      // handle the event, otherwise, the popup should handle it.
      if (popupFrame &&
          !nsContentUtils::ContentIsCrossDocDescendantOf(
             framePresContext->GetPresShell()->GetDocument(),
             popupFrame->GetContent())) {
        frame = popupFrame;
      }
    }

    bool captureRetarget = false;
    if (capturingContent) {
      // If a capture is active, determine if the docshell is visible. If not,
      // clear the capture and target the mouse event normally instead. This
      // would occur if the mouse button is held down while a tab change occurs.
      // If the docshell is visible, look for a scrolling container.
      bool vis;
      nsCOMPtr<nsISupports> supports = mPresContext->GetContainer();
      nsCOMPtr<nsIBaseWindow> baseWin(do_QueryInterface(supports));
      if (baseWin && NS_SUCCEEDED(baseWin->GetVisibility(&vis)) && vis) {
        captureRetarget = gCaptureInfo.mRetargetToElement;
        if (!captureRetarget) {
          // A check was already done above to ensure that capturingContent is
          // in this presshell.
          NS_ASSERTION(capturingContent->GetCurrentDoc() == GetDocument(),
                       "Unexpected document");
          nsIFrame* captureFrame = capturingContent->GetPrimaryFrame();
          if (captureFrame) {
            if (capturingContent->Tag() == nsGkAtoms::select &&
                capturingContent->IsHTML()) {
              // a dropdown <select> has a child in its selectPopupList and we should
              // capture on that instead.
              nsIFrame* childFrame = captureFrame->GetChildList(nsIFrame::kSelectPopupList).FirstChild();
              if (childFrame) {
                captureFrame = childFrame;
              }
            }

            // scrollable frames should use the scrolling container as
            // the root instead of the document
            nsIScrollableFrame* scrollFrame = do_QueryFrame(captureFrame);
            if (scrollFrame) {
              frame = scrollFrame->GetScrolledFrame();
            }
          }
        }
      }
      else {
        ClearMouseCapture(nullptr);
        capturingContent = nullptr;
      }
    }

    // all touch events except for touchstart use a captured target
    if (aEvent->eventStructType == NS_TOUCH_EVENT &&
        aEvent->message != NS_TOUCH_START) {
      captureRetarget = true;
    }

    bool isWindowLevelMouseExit = (aEvent->message == NS_MOUSE_EXIT) &&
      (static_cast<nsMouseEvent*>(aEvent)->exit == nsMouseEvent::eTopLevel);

    // Get the frame at the event point. However, don't do this if we're
    // capturing and retargeting the event because the captured frame will
    // be used instead below. Also keep using the root frame if we're dealing
    // with a window-level mouse exit event since we want to start sending
    // mouse out events at the root EventStateManager.
    if (!captureRetarget && !isWindowLevelMouseExit) {
      nsPoint eventPoint;
      if (aEvent->message == NS_TOUCH_START) {
        nsTouchEvent* touchEvent = static_cast<nsTouchEvent*>(aEvent);
        // if there is only one touch in this touchstart event, assume that it is
        // the start of a new touch session and evict any old touches in the
        // queue
        if (touchEvent->touches.Length() == 1) {
          nsTArray<nsCOMPtr<nsIDOMTouch> > touches;
          gCaptureTouchList.Enumerate(&AppendToTouchList, (void *)&touches);
          for (uint32_t i = 0; i < touches.Length(); ++i) {
            EvictTouchPoint(touches[i]);
          }
        }
        // if this is a continuing session, ensure that all these events are
        // in the same document by taking the target of the events already in
        // the capture list
        nsCOMPtr<nsIContent> anyTarget;
        if (gCaptureTouchList.Count() > 0) {
          gCaptureTouchList.Enumerate(&FindAnyTarget, &anyTarget);
        } else {
          gPreventMouseEvents = false;
        }

        // Add any new touches to the queue
        for (int32_t i = touchEvent->touches.Length(); i; ) {
          --i;
          nsIDOMTouch *touch = touchEvent->touches[i];
          nsDOMTouch *domtouch = static_cast<nsDOMTouch*>(touch);
          touch->mMessage = aEvent->message;

          int32_t id = 0;
          touch->GetIdentifier(&id);
          if (!gCaptureTouchList.Get(id, nullptr)) {
            // This event is a new touch. Mark it as a changedTouch and
            // add it to the queue.
            touch->mChanged = true;

            // find the target for this touch
            uint32_t flags = 0;
            eventPoint = nsLayoutUtils::GetEventCoordinatesRelativeTo(aEvent,
                                                              touch->mRefPoint,
                                                              frame);
            nsIFrame* target =
                          FindFrameTargetedByInputEvent(aEvent->eventStructType,
                                                        frame,
                                                        eventPoint,
                                                        flags);
            if (target && !anyTarget) {
              target->GetContentForEvent(aEvent, getter_AddRefs(anyTarget));
              while (anyTarget && !anyTarget->IsElement()) {
                anyTarget = anyTarget->GetParent();
              }
              domtouch->SetTarget(anyTarget);
              gCaptureTouchList.Put(id, touch);
            } else {
              nsIFrame* newTargetFrame = nullptr;
              for (nsIFrame* f = target; f;
                   f = nsLayoutUtils::GetParentOrPlaceholderForCrossDoc(f)) {
                if (f->PresContext()->Document() == anyTarget->OwnerDoc()) {
                  newTargetFrame = f;
                  break;
                }
                // We must be in a subdocument so jump directly to the root frame.
                // GetParentOrPlaceholderForCrossDoc gets called immediately to
                // jump up to the containing document.
                f = f->PresContext()->GetPresShell()->GetRootFrame();
              }
    
              // if we couldn't find a target frame in the same document as
              // anyTarget, remove the touch from the capture touch list, as
              // well as the event->touches array. touchmove events that aren't
              // in the captured touch list will be discarded
              if (!newTargetFrame) {
                touchEvent->touches.RemoveElementAt(i);
              } else {
                target = newTargetFrame;
                nsCOMPtr<nsIContent> targetContent;
                target->GetContentForEvent(aEvent, getter_AddRefs(targetContent));
                while (targetContent && !targetContent->IsElement()) {
                  targetContent = targetContent->GetParent();
                }
                touch->SetTarget(targetContent);
                gCaptureTouchList.Put(id, touch);
              }
            }
            if (target) {
              frame = target;
            }
          } else {
            // This touch is an old touch, we need to ensure that is not
            // marked as changed and set its target correctly
            touch->mChanged = false;
            int32_t id;
            touch->GetIdentifier(&id);

            nsCOMPtr<nsIDOMTouch> oldTouch;
            gCaptureTouchList.Get(id, getter_AddRefs(oldTouch));
            if (oldTouch) {
              nsCOMPtr<nsPIDOMEventTarget> targetPtr;
              oldTouch->GetTarget(getter_AddRefs(targetPtr));
              domtouch->SetTarget(targetPtr);
              gCaptureTouchList.Put(id, touch);
            }
          }
        }
      } else {
        eventPoint = nsLayoutUtils::GetEventCoordinatesRelativeTo(aEvent, frame);
      }
      uint32_t flags = 0;
      if (aEvent->eventStructType == NS_MOUSE_EVENT &&
          static_cast<nsMouseEvent*>(aEvent)->ignoreRootScrollFrame) {
        flags |= INPUT_IGNORE_ROOT_SCROLL_FRAME;
      }
      nsIFrame* target =
        FindFrameTargetedByInputEvent(aEvent->eventStructType, frame, eventPoint, flags);
      if (target) {
        frame = target;
      }
    }

    // if a node is capturing the mouse, check if the event needs to be
    // retargeted at the capturing content instead. This will be the case when
    // capture retargeting is being used, no frame was found or the frame's
    // content is not a descendant of the capturing content.
    if (capturingContent &&
        (gCaptureInfo.mRetargetToElement || !frame->GetContent() ||
         !nsContentUtils::ContentIsCrossDocDescendantOf(frame->GetContent(),
                                                        capturingContent))) {
      // A check was already done above to ensure that capturingContent is
      // in this presshell.
      NS_ASSERTION(capturingContent->GetCurrentDoc() == GetDocument(),
                   "Unexpected document");
      nsIFrame* capturingFrame = capturingContent->GetPrimaryFrame();
      if (capturingFrame) {
        frame = capturingFrame;
      }
    }

    // Suppress mouse event if it's being targeted at an element inside
    // a document which needs events suppressed
    if (aEvent->eventStructType == NS_MOUSE_EVENT &&
        frame->PresContext()->Document()->EventHandlingSuppressed()) {
      if (aEvent->message == NS_MOUSE_BUTTON_DOWN) {
        mNoDelayedMouseEvents = true;
      } else if (!mNoDelayedMouseEvents && aEvent->message == NS_MOUSE_BUTTON_UP) {
        nsDelayedEvent* event =
          new nsDelayedMouseEvent(static_cast<nsMouseEvent*>(aEvent));
        if (!mDelayedEvents.AppendElement(event)) {
          delete event;
        }
      }

      return NS_OK;
    }

    PresShell* shell =
        static_cast<PresShell*>(frame->PresContext()->PresShell());
    switch (aEvent->message) {
      case NS_TOUCH_MOVE:
      case NS_TOUCH_CANCEL:
      case NS_TOUCH_END: {
        // get the correct shell to dispatch to
        nsTouchEvent* touchEvent = static_cast<nsTouchEvent*>(aEvent);
        nsTArray<nsCOMPtr<nsIDOMTouch> >  &touches = touchEvent->touches;
        for (uint32_t i = 0; i < touches.Length(); ++i) {
          nsIDOMTouch *touch = touches[i];
          if (!touch) {
            break;
          }
  
          int32_t id;
          touch->GetIdentifier(&id);
          nsCOMPtr<nsIDOMTouch> oldTouch;
          gCaptureTouchList.Get(id, getter_AddRefs(oldTouch));
          if (!oldTouch) {
            break;
          }
  
          nsCOMPtr<nsPIDOMEventTarget> targetPtr;
          oldTouch->GetTarget(getter_AddRefs(targetPtr));
          nsCOMPtr<nsIContent> content = do_QueryInterface(targetPtr);
          if (!content) {
            break;
          }

          nsIFrame* contentFrame = content->GetPrimaryFrame();
          if (!contentFrame) {
            break;
          }

          shell = static_cast<PresShell*>(
                      contentFrame->PresContext()->PresShell());
          if (shell) {
            break;
          }
        }
        break;
      }
    }

    // Check if we have an active EventStateManager which isn't the
    // EventStateManager of the current PresContext.
    // If that is the case, and mouse is over some ancestor document,
    // forward event handling to the active document.
    // This way content can get mouse events even when
    // mouse is over the chrome or outside the window.
    //
    // Note, currently for backwards compatibility we don't forward mouse events
    // to the active document when mouse is over some subdocument.
    nsEventStateManager* activeESM =
      nsEventStateManager::GetActiveEventStateManager();
    if (activeESM && NS_IS_MOUSE_EVENT(aEvent) &&
        activeESM != shell->GetPresContext()->EventStateManager() &&
        static_cast<nsEventStateManager*>(activeESM)->GetPresContext()) {
      nsIPresShell* activeShell =
        static_cast<nsEventStateManager*>(activeESM)->GetPresContext()->GetPresShell();
      if (activeShell &&
          nsContentUtils::ContentIsCrossDocDescendantOf(activeShell->GetDocument(),
                                                        shell->GetDocument())) {
        shell = static_cast<PresShell*>(activeShell);
        frame = shell->GetRootFrame();
      }
    }

    if (shell != this) {
      // Handle the event in the correct shell.
      // Prevent deletion until we're done with event handling (bug 336582).
      nsCOMPtr<nsIPresShell> kungFuDeathGrip(shell);
      // We pass the subshell's root frame as the frame to start from. This is
      // the only correct alternative; if the event was captured then it
      // must have been captured by us or some ancestor shell and we
      // now ask the subshell to dispatch it normally.
      return shell->HandlePositionedEvent(frame, aEvent, aEventStatus);
    }

    return HandlePositionedEvent(frame, aEvent, aEventStatus);
  }
  
  nsresult rv = NS_OK;
  
  if (frame) {
    PushCurrentEventInfo(nullptr, nullptr);

    // key and IME related events go to the focused frame in this DOM window.
    if (NS_IsEventTargetedAtFocusedContent(aEvent)) {
      mCurrentEventContent = nullptr;

      nsCOMPtr<nsPIDOMWindow> window =
        do_QueryInterface(mDocument->GetWindow());
      nsCOMPtr<nsPIDOMWindow> focusedWindow;
      nsCOMPtr<nsIContent> eventTarget =
        nsFocusManager::GetFocusedDescendant(window, false,
                                             getter_AddRefs(focusedWindow));

      // otherwise, if there is no focused content or the focused content has
      // no frame, just use the root content. This ensures that key events
      // still get sent to the window properly if nothing is focused or if a
      // frame goes away while it is focused.
      if (!eventTarget || !eventTarget->GetPrimaryFrame()) {
        nsCOMPtr<nsIDOMHTMLDocument> htmlDoc = do_QueryInterface(mDocument);
        if (htmlDoc) {
          nsCOMPtr<nsIDOMHTMLElement> body;
          htmlDoc->GetBody(getter_AddRefs(body));
          eventTarget = do_QueryInterface(body);
          if (!eventTarget) {
            eventTarget = mDocument->GetRootElement();
          }
        } else {
          eventTarget = mDocument->GetRootElement();
        }
      }

      if (aEvent->message == NS_KEY_DOWN) {
        NS_IF_RELEASE(gKeyDownTarget);
        NS_IF_ADDREF(gKeyDownTarget = eventTarget);
      }
      else if ((aEvent->message == NS_KEY_PRESS || aEvent->message == NS_KEY_UP) &&
               gKeyDownTarget) {
        // If a different element is now focused for the keypress/keyup event
        // than what was focused during the keydown event, check if the new
        // focused element is not in a chrome document any more, and if so,
        // retarget the event back at the keydown target. This prevents a
        // content area from grabbing the focus from chrome in-between key
        // events.
        if (eventTarget &&
            nsContentUtils::IsChromeDoc(gKeyDownTarget->GetCurrentDoc()) !=
            nsContentUtils::IsChromeDoc(eventTarget->GetCurrentDoc())) {
          eventTarget = gKeyDownTarget;
        }

        if (aEvent->message == NS_KEY_UP) {
          NS_RELEASE(gKeyDownTarget);
        }
      }

      mCurrentEventFrame = nullptr;
      nsIDocument* targetDoc = eventTarget ? eventTarget->OwnerDoc() : nullptr;
      if (targetDoc && targetDoc != mDocument) {
        PopCurrentEventInfo();
        nsCOMPtr<nsIPresShell> shell = targetDoc->GetShell();
        if (shell) {
          rv = static_cast<PresShell*>(shell.get())->
            HandleRetargetedEvent(aEvent, aEventStatus, eventTarget);
        }
        return rv;
      } else {
        mCurrentEventContent = eventTarget;
      }
        
      if (!mCurrentEventContent || !GetCurrentEventFrame() ||
          InZombieDocument(mCurrentEventContent)) {
        rv = RetargetEventToParent(aEvent, aEventStatus);
        PopCurrentEventInfo();
        return rv;
      }
    } else {
      mCurrentEventFrame = frame;
    }
    if (GetCurrentEventFrame()) {
      rv = HandleEventInternal(aEvent, aEventStatus);
    }
  
#ifdef DEBUG
    ShowEventTargetDebug();
#endif
    PopCurrentEventInfo();
  } else {
    // Activation events need to be dispatched even if no frame was found, since
    // we don't want the focus to be out of sync.

    if (!NS_EVENT_NEEDS_FRAME(aEvent)) {
      mCurrentEventFrame = nullptr;
      return HandleEventInternal(aEvent, aEventStatus);
    }
    else if (NS_IS_KEY_EVENT(aEvent)) {
      // Keypress events in new blank tabs should not be completely thrown away.
      // Retarget them -- the parent chrome shell might make use of them.
      return RetargetEventToParent(aEvent, aEventStatus);
    }
  }

  return rv;
}

#ifdef ANDROID
nsIDocument*
PresShell::GetTouchEventTargetDocument()
{
  nsPresContext* context = GetPresContext();
  if (!context || !context->IsRoot()) {
    return nullptr;
  }

  nsCOMPtr<nsISupports> container = context->GetContainer();
  nsCOMPtr<nsIDocShellTreeItem> shellAsTreeItem = do_QueryInterface(container);
  if (!shellAsTreeItem) {
    return nullptr;
  }

  nsCOMPtr<nsIDocShellTreeOwner> owner;
  shellAsTreeItem->GetTreeOwner(getter_AddRefs(owner));
  if (!owner) {
    return nullptr;
  }

  // now get the primary content shell (active tab)
  nsCOMPtr<nsIDocShellTreeItem> item;
  owner->GetPrimaryContentShell(getter_AddRefs(item));
  nsCOMPtr<nsIDocShell> childDocShell = do_QueryInterface(item);
  nsCOMPtr<nsIDocument> result = do_GetInterface(childDocShell);
  return result;
}
#endif

#ifdef DEBUG
void
PresShell::ShowEventTargetDebug()
{
  if (nsFrame::GetShowEventTargetFrameBorder() &&
      GetCurrentEventFrame()) {
    if (mDrawEventTargetFrame) {
      mDrawEventTargetFrame->InvalidateFrame();
    }

    mDrawEventTargetFrame = mCurrentEventFrame;
    mDrawEventTargetFrame->InvalidateFrame();
  }
}
#endif

nsresult
PresShell::HandlePositionedEvent(nsIFrame*      aTargetFrame,
                                 nsGUIEvent*    aEvent,
                                 nsEventStatus* aEventStatus)
{
  nsresult rv = NS_OK;
  
  PushCurrentEventInfo(nullptr, nullptr);
  
  mCurrentEventFrame = aTargetFrame;

  if (mCurrentEventFrame) {
    nsCOMPtr<nsIContent> targetElement;
    mCurrentEventFrame->GetContentForEvent(aEvent,
                                           getter_AddRefs(targetElement));

    // If there is no content for this frame, target it anyway.  Some
    // frames can be targeted but do not have content, particularly
    // windows with scrolling off.
    if (targetElement) {
      // Bug 103055, bug 185889: mouse events apply to *elements*, not all
      // nodes.  Thus we get the nearest element parent here.
      // XXX we leave the frame the same even if we find an element
      // parent, so that the text frame will receive the event (selection
      // and friends are the ones who care about that anyway)
      //
      // We use weak pointers because during this tight loop, the node
      // will *not* go away.  And this happens on every mousemove.
      while (targetElement && !targetElement->IsElement()) {
        targetElement = targetElement->GetParent();
      }

      // If we found an element, target it.  Otherwise, target *nothing*.
      if (!targetElement) {
        mCurrentEventContent = nullptr;
        mCurrentEventFrame = nullptr;
      } else if (targetElement != mCurrentEventContent) {
        mCurrentEventContent = targetElement;
      }
    }
  }

  if (GetCurrentEventFrame()) {
    rv = HandleEventInternal(aEvent, aEventStatus);
  }

#ifdef DEBUG
  ShowEventTargetDebug();
#endif
  PopCurrentEventInfo();
  return rv;
}

nsresult
PresShell::HandleEventWithTarget(nsEvent* aEvent, nsIFrame* aFrame,
                                 nsIContent* aContent, nsEventStatus* aStatus)
{
  PushCurrentEventInfo(aFrame, aContent);
  nsresult rv = HandleEventInternal(aEvent, aStatus);
  PopCurrentEventInfo();
  return rv;
}

static bool CanHandleContextMenuEvent(nsMouseEvent* aMouseEvent,
                                        nsIFrame* aFrame)
{
#if defined(XP_MACOSX) && defined(MOZ_XUL)
  nsXULPopupManager* pm = nsXULPopupManager::GetInstance();
  if (pm) {
    nsIFrame* popupFrame = pm->GetTopPopup(ePopupTypeMenu);
    if (popupFrame) {
      // context menus should not be opened while another menu is open on Mac,
      // so return false so that the event is not fired.
      if (aMouseEvent->context == nsMouseEvent::eContextMenuKey) {
        return false;
      } else if (aMouseEvent->widget) {
         nsWindowType windowType;
         aMouseEvent->widget->GetWindowType(windowType);
         if (windowType == eWindowType_popup) {
           for (nsIFrame* current = aFrame; current;
                current = nsLayoutUtils::GetCrossDocParentFrame(current)) {
             if (current->GetType() == nsGkAtoms::menuPopupFrame) {
               return false;
             }
           }
         }
      }
    }
  }
#endif
  return true;
}

nsresult
PresShell::HandleEventInternal(nsEvent* aEvent, nsEventStatus* aStatus)
{
  nsRefPtr<nsEventStateManager> manager = mPresContext->EventStateManager();
  nsresult rv = NS_OK;

  if (!NS_EVENT_NEEDS_FRAME(aEvent) || GetCurrentEventFrame()) {
    bool touchIsNew = false;
    bool isHandlingUserInput = false;

    // XXX How about IME events and input events for plugins?
    if (NS_IS_TRUSTED_EVENT(aEvent)) {
      switch (aEvent->message) {
      case NS_KEY_PRESS:
      case NS_KEY_DOWN:
      case NS_KEY_UP: {
        nsIDocument *doc = mCurrentEventContent ?
                           mCurrentEventContent->OwnerDoc() : nullptr;
        nsIDocument* root = nullptr;
        if (static_cast<const nsKeyEvent*>