author alwu <>
Mon, 07 Jan 2019 19:57:48 +0000
changeset 512757 0e229bbdaae5c8fa9f83796c628a4fdf88f057ba
parent 511783 996bf60e0fce90cc42e7b59201d56ba0947b8cf2
child 523703 47dfb7c2aa932121e3eb769c87f7d206ab059437
permissions -rw-r--r--
Bug 1513039 - part5 : log warning when autoplay is blocked. r=cpearce,karlt Wrap 'nsContentUtils::ReportToConsole()' to reduce necessary input parameters and call it when we need to log error or warning message. Show the warning when autoplay is blocked. For web audio, this restores the console messages removed in part4 and also reports the same message when the AudioContext is blocked in the constructor. Differential Revision:

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


#include "nsAutoPtr.h"
#include "nsCSSPropertyIDSet.h"
#include "nsTHashtable.h"
#include "nsHashKeys.h"
#include "nsTArray.h"
#include "nsRegion.h"
#include "nsIFrame.h"
#include "DisplayItemClip.h"
#include "mozilla/gfx/MatrixFwd.h"
#include "mozilla/layers/LayersTypes.h"
#include "LayerState.h"
#include "Layers.h"
#include "LayerUserData.h"
#include "nsDisplayItemTypes.h"
#include "TransformClipNode.h"

class nsDisplayListBuilder;
class nsDisplayList;
class nsDisplayItem;
class gfxContext;
class nsDisplayItemGeometry;
class nsDisplayMasksAndClipPaths;

namespace mozilla {
struct ActiveScrolledRoot;
struct DisplayItemClipChain;
namespace layers {
class ContainerLayer;
class LayerManager;
class BasicLayerManager;
class PaintedLayer;
class ImageLayer;
}  // namespace layers

class FrameLayerBuilder;
class LayerManagerData;
class PaintedLayerData;
class ContainerState;
class PaintedDisplayItemLayerUserData;

enum class DisplayItemEntryType {

 * Retained data storage:
 * Each layer manager (widget, and inactive) stores a LayerManagerData object
 * that keeps a hash-set of DisplayItemData items that were drawn into it.
 * Each frame also keeps a list of DisplayItemData pointers that were
 * created for that frame. DisplayItemData objects manage these lists
 * automatically.
 * During layer construction we update the data in the LayerManagerData object,
 * marking items that are modified. At the end we sweep the LayerManagerData
 * hash-set and remove all items that haven't been modified.

 * Retained data for a display item.
class DisplayItemData final {
  friend class FrameLayerBuilder;
  friend class ContainerState;

  uint32_t GetDisplayItemKey() { return mDisplayItemKey; }
  layers::Layer* GetLayer() const { return mLayer; }
  nsDisplayItemGeometry* GetGeometry() const { return mGeometry.get(); }
  const DisplayItemClip& GetClip() const { return mClip; }
  void Invalidate() { mIsInvalid = true; }
  void ClearAnimationCompositorState();
  void SetItem(nsDisplayItem* aItem) { mItem = aItem; }
  nsDisplayItem* GetItem() const { return mItem; }

  bool HasMergedFrames() const { return mFrameList.Length() > 1; }

  static DisplayItemData* AssertDisplayItemData(DisplayItemData* aData);

  void* operator new(size_t sz, nsPresContext* aPresContext) {
    // Check the recycle list first.
    return aPresContext->PresShell()->AllocateByObjectID(
        eArenaObjectID_DisplayItemData, sz);

  nsrefcnt AddRef() {
    if (mRefCnt == UINT32_MAX) {
      NS_WARNING("refcount overflow, leaking object");
      return mRefCnt;
    NS_LOG_ADDREF(this, mRefCnt, "ComputedStyle", sizeof(ComputedStyle));
    return mRefCnt;

  nsrefcnt Release() {
    if (mRefCnt == UINT32_MAX) {
      NS_WARNING("refcount overflow, leaking object");
      return mRefCnt;
    NS_LOG_RELEASE(this, mRefCnt, "ComputedStyle");
    if (mRefCnt == 0) {
      return 0;
    return mRefCnt;

  RefPtr<TransformClipNode> mTransform;
  RefPtr<TransformClipNode> mOldTransform;

  DisplayItemData(LayerManagerData* aParent, uint32_t aKey,
                  layers::Layer* aLayer, nsIFrame* aFrame = nullptr);

   * Removes any references to this object from frames
   * in mFrameList.

  void Destroy() {
    // Get the pres context.
    RefPtr<nsPresContext> presContext = mFrameList[0]->PresContext();

    // Call our destructor.

    // Don't let the memory be freed, since it will be recycled
    // instead. Don't call the global operator delete.

   * Associates this DisplayItemData with a frame, and adds it
   * to the LayerManagerDataProperty list on the frame.
  void AddFrame(nsIFrame* aFrame);
  void RemoveFrame(nsIFrame* aFrame);
  const nsRegion& GetChangedFrameInvalidations();

   * Updates the contents of this item to a new set of data, instead of
   * allocating a new object. Set the passed in parameters, and clears the opt
   * layer and inactive manager. Parent, and display item key are assumed to be
   * the same.
   * EndUpdate must be called before the end of the transaction to complete the
   * update.
  void BeginUpdate(layers::Layer* aLayer, LayerState aState, bool aFirstUpdate,
                   nsDisplayItem* aItem = nullptr);
  void BeginUpdate(layers::Layer* aLayer, LayerState aState,
                   nsDisplayItem* aItem, bool aIsReused, bool aIsMerged);

   * Completes the update of this, and removes any references to data that won't
   * live longer than the transaction.
   * Updates the geometry, frame list and clip.
   * For items within a PaintedLayer, a geometry object must be specified to
   * retain until the next transaction.
  void EndUpdate(nsAutoPtr<nsDisplayItemGeometry> aGeometry);
  void EndUpdate();

  uint32_t mRefCnt;
  LayerManagerData* mParent;
  RefPtr<layers::Layer> mLayer;
  RefPtr<layers::Layer> mOptLayer;
  RefPtr<layers::BasicLayerManager> mInactiveManager;
  AutoTArray<nsIFrame*, 1> mFrameList;
  nsAutoPtr<nsDisplayItemGeometry> mGeometry;
  DisplayItemClip mClip;
  uint32_t mDisplayItemKey;
  LayerState mLayerState;

   * Temporary stoarage of the display item being referenced, only valid between
   * BeginUpdate and EndUpdate.
  nsDisplayItem* mItem;
  nsRegion mChangedFrameInvalidations;

   * Used to track if data currently stored in mFramesWithLayers (from an
   * existing paint) has been updated in the current paint.
  bool mUsed;
  bool mIsInvalid;
  bool mReusedItem;

class RefCountedRegion {
  ~RefCountedRegion() = default;


  RefCountedRegion() : mIsInfinite(false) {}
  nsRegion mRegion;
  bool mIsInfinite;

struct AssignedDisplayItem {
  AssignedDisplayItem(nsDisplayItem* aItem, LayerState aLayerState,
                      DisplayItemData* aData, const nsRect& aContentRect,
                      DisplayItemEntryType aType, const bool aHasOpacity,
                      const RefPtr<TransformClipNode>& aTransform);

  nsDisplayItem* mItem;
  LayerState mLayerState;
  DisplayItemData* mDisplayItemData;
  nsRect mContentRect;

   * If the display item is being rendered as an inactive
   * layer, then this stores the layer manager being
   * used for the inactive transaction.
  RefPtr<layers::LayerManager> mInactiveLayerManager;
  RefPtr<TransformClipNode> mTransform;
  DisplayItemEntryType mType;

  bool mReused;
  bool mMerged;
  bool mHasOpacity;
  bool mHasTransform;
  bool mHasPaintRect;

struct ContainerLayerParameters {
      : mXScale(1),
        mBackgroundColor(NS_RGBA(0, 0, 0, 0)),
        mLayerCreationHint(layers::LayerManager::NONE) {}
  ContainerLayerParameters(float aXScale, float aYScale)
      : mXScale(aXScale),
        mBackgroundColor(NS_RGBA(0, 0, 0, 0)),
        mLayerCreationHint(layers::LayerManager::NONE) {}
  ContainerLayerParameters(float aXScale, float aYScale,
                           const nsIntPoint& aOffset,
                           const ContainerLayerParameters& aParent)
      : mXScale(aXScale),
        mLayerCreationHint(aParent.mLayerCreationHint) {}

  float mXScale, mYScale;

  LayoutDeviceToLayerScale2D Scale() const {
    return LayoutDeviceToLayerScale2D(mXScale, mYScale);

   * If non-null, the rectangle in which BuildContainerLayerFor stores the
   * visible rect of the layer, in the coordinate system of the created layer.
  nsIntRect* mLayerContentsVisibleRect;

   * An offset to apply to all child layers created.
  nsIntPoint mOffset;

  LayerIntPoint Offset() const {
    return LayerIntPoint::FromUnknownPoint(mOffset);

  nscolor mBackgroundColor;
  const ActiveScrolledRoot* mScrollMetadataASR;
  const ActiveScrolledRoot* mCompositorASR;

  bool mInTransformedSubtree;
  bool mInActiveTransformedSubtree;
  bool mDisableSubpixelAntialiasingInDescendants;
  bool mForEventsAndPluginsOnly;
  layers::LayerManager::PaintedLayerCreationHint mLayerCreationHint;

   * When this is false, PaintedLayer coordinates are drawn to with an integer
   * translation and the scale in mXScale/mYScale.
  bool AllowResidualTranslation() {
    // If we're in a transformed subtree, but no ancestor transform is actively
    // changing, we'll use the residual translation when drawing into the
    // PaintedLayer to ensure that snapping exactly matches the ideal transform.
    return mInTransformedSubtree && !mInActiveTransformedSubtree;

 * The FrameLayerBuilder is responsible for converting display lists
 * into layer trees. Every LayerManager needs a unique FrameLayerBuilder
 * to build layers.
 * The most important API in this class is BuildContainerLayerFor. This
 * method takes a display list as input and constructs a ContainerLayer
 * with child layers that render the contents of the display list. It
 * records the relationship between frames and layers.
 * That data enables us to retain layer trees. When constructing a
 * ContainerLayer, we first check to see if there's an existing
 * ContainerLayer for the same frame that can be recycled. If we recycle
 * it, we also try to reuse its existing PaintedLayer children to render
 * the display items without layers of their own. The idea is that by
 * recycling layers deterministically, we can ensure that when nothing
 * changes in a display list, we will reuse the existing layers without
 * changes.
 * We expose a GetLeafLayerFor method that can be called by display items
 * that make their own layers (e.g. canvas and video); this method
 * locates the last layer used to render the display item, if any, and
 * return it as a candidate for recycling.
 * FrameLayerBuilder sets up PaintedLayers so that 0,0 in the Painted layer
 * corresponds to the (pixel-snapped) top-left of the aAnimatedGeometryRoot.
 * It sets up ContainerLayers so that 0,0 in the container layer
 * corresponds to the snapped top-left of the display item reference frame.
 * When we construct a container layer, we know the transform that will be
 * applied to the layer. If the transform scales the content, we can get
 * better results when intermediate buffers are used by pushing some scale
 * from the container's transform down to the children. For PaintedLayer
 * children, the scaling can be achieved by changing the size of the layer
 * and drawing into it with increased or decreased resolution. By convention,
 * integer types (nsIntPoint/nsIntSize/nsIntRect/nsIntRegion) are all in layer
 * coordinates, post-scaling, whereas appunit types are all pre-scaling.
class FrameLayerBuilder : public layers::LayerUserData {
  typedef layers::ContainerLayer ContainerLayer;
  typedef layers::Layer Layer;
  typedef layers::PaintedLayer PaintedLayer;
  typedef layers::ImageLayer ImageLayer;
  typedef layers::LayerManager LayerManager;
  typedef layers::BasicLayerManager BasicLayerManager;
  typedef layers::EventRegions EventRegions;

  ~FrameLayerBuilder() override;

  static gfx::Size ChooseScale(nsIFrame* aContainerFrame,
                               nsDisplayItem* aContainerItem,
                               const nsRect& aVisibleRect, float aXScale,
                               float aYScale, const gfx::Matrix& aTransform2d,
                               bool aCanDraw2D);

  static void Shutdown();

  void Init(nsDisplayListBuilder* aBuilder, LayerManager* aManager,
            PaintedLayerData* aLayerData = nullptr,
            bool aIsInactiveLayerManager = false,
            const DisplayItemClip* aInactiveLayerClip = nullptr);

   * Call this to notify that we have just started a transaction on the
   * retained layer manager aManager.
  void DidBeginRetainedLayerTransaction(LayerManager* aManager);

   * Call this just before we end a transaction.
  void WillEndTransaction();

   * Call this after we end a transaction.
  void DidEndTransaction();

  enum {
     * Set this when pulling an opaque background color from behind the
     * container layer into the container doesn't change the visual results,
     * given the effects you're going to apply to the container layer.
     * For example, this is compatible with opacity or clipping/masking, but
     * not with non-OVER blend modes or filters.
   * Build a container layer for a display item that contains a child
   * list, either reusing an existing one or creating a new one. It
   * sets the container layer children to layers which together render
   * the contents of the display list. It reuses existing layers from
   * the retained layer manager if possible.
   * aContainerItem may be null, in which case we construct a root layer.
   * This gets called by display list code. It calls BuildLayer on the
   * items in the display list, making items with their own layers
   * children of the new container, and assigning all other items to
   * PaintedLayer children created and managed by the FrameLayerBuilder.
   * Returns a layer with clip rect cleared; it is the
   * caller's responsibility to add any clip rect. The visible region
   * is set based on what's in the layer.
   * The container layer is transformed by aTransform (if non-null), and
   * the result is transformed by the scale factors in aContainerParameters.
   * aChildren is modified due to display item merging and flattening.
   * The visible region of the returned layer is set only if aContainerItem
   * is null.
  already_AddRefed<ContainerLayer> BuildContainerLayerFor(
      nsDisplayListBuilder* aBuilder, LayerManager* aManager,
      nsIFrame* aContainerFrame, nsDisplayItem* aContainerItem,
      nsDisplayList* aChildren,
      const ContainerLayerParameters& aContainerParameters,
      const gfx::Matrix4x4* aTransform, uint32_t aFlags = 0);

   * Get a retained layer for a display item that needs to create its own
   * layer for rendering (i.e. under nsDisplayItem::BuildLayer). Returns
   * null if no retained layer is available, which usually means that this
   * display item didn't have a layer before so the caller will
   * need to create one.
   * Returns a layer with clip rect cleared; it is the
   * caller's responsibility to add any clip rect and set the visible
   * region.
  Layer* GetLeafLayerFor(nsDisplayListBuilder* aBuilder, nsDisplayItem* aItem);

   * Call this to force all retained layers to be discarded and recreated at
   * the next paint.
  static void InvalidateAllLayers(LayerManager* aManager);
  static void InvalidateAllLayersForFrame(nsIFrame* aFrame);

   * Call this to determine if a frame has a dedicated (non-Painted) layer
   * for the given display item key. If there isn't one, we return null,
   * otherwise we return the layer.
  static Layer* GetDedicatedLayer(nsIFrame* aFrame,
                                  DisplayItemType aDisplayItemType);

  using CompositorAnimatableDisplayItemTypes =
      Array<DisplayItemType, nsCSSPropertyIDSet::CompositorAnimatableCount()>;
  using AnimationGenerationCallback = std::function<bool(
      const Maybe<uint64_t>& aGeneration, DisplayItemType aDisplayItemType)>;
   * Enumerates layers for the given display item types and calls |aCallback|
   * with the animation generation for the layer.  If there is no corresponding
   * layer for the display item or the layer has no animation, the animation
   * generation is Nothing().
   * The enumeration stops if |aCallback| returns false.
  static void EnumerateGenerationForDedicatedLayers(
      const nsIFrame* aFrame,
      const CompositorAnimatableDisplayItemTypes& aDisplayItemTypes,
      const AnimationGenerationCallback& aCallback);

   * This callback must be provided to EndTransaction. The callback data
   * must be the nsDisplayListBuilder containing this FrameLayerBuilder.
   * This function can be called multiple times in a row to draw
   * different regions. This will occur when, for example, progressive paint is
   * enabled. In these cases aDirtyRegion can be used to specify a larger region
   * than aRegionToDraw that will be drawn during the transaction, possibly
   * allowing the callback to make optimizations.
  static void DrawPaintedLayer(PaintedLayer* aLayer, gfxContext* aContext,
                               const nsIntRegion& aRegionToDraw,
                               const nsIntRegion& aDirtyRegion,
                               mozilla::layers::DrawRegionClip aClip,
                               const nsIntRegion& aRegionToInvalidate,
                               void* aCallbackData);

   * Dumps this FrameLayerBuilder's retained layer manager's retained
   * layer tree. Defaults to dumping to stdout in non-HTML format.
  static void DumpRetainedLayerTree(LayerManager* aManager,
                                    std::stringstream& aStream,
                                    bool aDumpHtml = false);

   * Returns the most recently allocated geometry item for the given display
   * item.
   * XXX(seth): The current implementation must iterate through all display
   * items allocated for this display item's frame. This may lead to O(n^2)
   * behavior in some situations.
  static nsDisplayItemGeometry* GetMostRecentGeometry(nsDisplayItem* aItem);

  /******* PRIVATE METHODS to FrameLayerBuilder.cpp ********/
  /* These are only in the public section because they need
   * to be called by file-scope helper functions in FrameLayerBuilder.cpp.

   * Record aItem as a display item that is rendered by the PaintedLayer
   * aLayer, with aClipRect, where aContainerLayerFrame is the frame
   * for the container layer this ThebesItem belongs to.
   * aItem must have an underlying frame.
   * @param aTopLeft offset from active scrolled root to reference frame
  void AddPaintedDisplayItem(PaintedLayerData* aLayerData,
                             AssignedDisplayItem& aAssignedDisplayItem,
                             ContainerState& aContainerState, Layer* aLayer);

   * Calls GetOldLayerForFrame on the underlying frame of the display item,
   * and each subsequent merged frame if no layer is found for the underlying
   * frame.
  Layer* GetOldLayerFor(nsDisplayItem* aItem,
                        nsDisplayItemGeometry** aOldGeometry = nullptr,
                        DisplayItemClip** aOldClip = nullptr);

  static DisplayItemData* GetOldDataFor(nsDisplayItem* aItem);

   * Return the layer that all display items of aFrame were assigned to in the
   * last paint, or nullptr if there was no single layer assigned to all of the
   * frame's display items (i.e. zero, or more than one).
   * This function is for testing purposes and not performance sensitive.
  template <class T>
  static T* GetDebugSingleOldLayerForFrame(nsIFrame* aFrame) {
    SmallPointerArray<DisplayItemData>& array = aFrame->DisplayItemData();

    Layer* layer = nullptr;
    for (DisplayItemData* data : array) {
      if (data->mLayer->GetType() != T::Type()) {
      if (layer && layer != data->mLayer) {
        // More than one layer assigned, bail.
        return nullptr;
      layer = data->mLayer;

    if (!layer) {
      return nullptr;

    return static_cast<T*>(layer);

   * Destroy any stored LayerManagerDataProperty and the associated data for
   * aFrame.
  static void DestroyDisplayItemDataFor(nsIFrame* aFrame);

  LayerManager* GetRetainingLayerManager() { return mRetainingManager; }

   * Returns true if the given display item was rendered during the previous
   * paint. Returns false otherwise.
  static bool HasRetainedDataFor(nsIFrame* aFrame, uint32_t aDisplayItemKey);

  typedef void (*DisplayItemDataCallback)(nsIFrame* aFrame,
                                          DisplayItemData* aItem);

   * Get the translation transform that was in aLayer when we last painted. It's
   * either the transform saved by SaveLastPaintTransform, or else the transform
   * that's currently in the layer (which must be an integer translation).
  nsIntPoint GetLastPaintOffset(PaintedLayer* aLayer);

   * Return the resolution at which we expect to render aFrame's contents,
   * assuming they are being painted to retained layers. This takes into account
   * the resolution the contents of the ContainerLayer containing aFrame are
   * being rendered at, as well as any currently-inactive transforms between
   * aFrame and that container layer.
  static gfxSize GetPaintedLayerScaleForFrame(nsIFrame* aFrame);

  static void RemoveFrameFromLayerManager(
      const nsIFrame* aFrame, SmallPointerArray<DisplayItemData>& aArray);

   * Given a frame and a display item key that uniquely identifies a
   * display item for the frame, find the layer that was last used to
   * render that display item. Returns null if there is no such layer.
   * This could be a dedicated layer for the display item, or a PaintedLayer
   * that renders many display items.
  DisplayItemData* GetOldLayerForFrame(
      nsIFrame* aFrame, uint32_t aDisplayItemKey,
      DisplayItemData* aOldData = nullptr,
      LayerManager* aOldLayerManager = nullptr);

   * Stores DisplayItemData associated with aFrame, stores the data in
   * mNewDisplayItemData.
  DisplayItemData* StoreDataForFrame(nsDisplayItem* aItem, Layer* aLayer,
                                     LayerState aState, DisplayItemData* aData);
  void StoreDataForFrame(nsIFrame* aFrame, uint32_t aDisplayItemKey,
                         Layer* aLayer, LayerState aState);

  friend class LayerManagerData;

  // Flash the area within the context clip if paint flashing is enabled.
  static void FlashPaint(gfxContext* aContext);

   * Get the DisplayItemData array associated with this frame, or null if one
   * doesn't exist.
   * Note that the pointer returned here is only valid so long as you don't
   * poke the LayerManagerData's mFramesWithLayers hashtable.
  DisplayItemData* GetDisplayItemData(nsIFrame* aFrame, uint32_t aKey);

   * Get the DisplayItemData associated with this frame / display item pair,
   * using the LayerManager instead of FrameLayerBuilder.
  static DisplayItemData* GetDisplayItemDataForManager(nsIFrame* aFrame,
                                                       uint32_t aDisplayItemKey,
                                                       LayerManager* aManager);
  static DisplayItemData* GetDisplayItemDataForManager(
      nsIFrame* aFrame, uint32_t aDisplayItemKey);
  static DisplayItemData* GetDisplayItemDataForManager(nsDisplayItem* aItem,
                                                       LayerManager* aManager);
  static DisplayItemData* GetDisplayItemDataForManager(nsIFrame* aFrame,
                                                       uint32_t aDisplayItemKey,
                                                       LayerManagerData* aData);

   * We store one of these for each display item associated with a
   * PaintedLayer, in a hashtable that maps each PaintedLayer to an array
   * of ClippedDisplayItems. (PaintedLayerItemsEntry is the hash entry
   * for that hashtable.)
   * These are only stored during the paint process, so that the
   * DrawPaintedLayer callback can figure out which items to draw for the
   * PaintedLayer.

  static void RecomputeVisibilityForItems(
      std::vector<AssignedDisplayItem>& aItems, nsDisplayListBuilder* aBuilder,
      const nsIntRegion& aRegionToDraw, nsRect& aPreviousRectToDraw,
      const nsIntPoint& aOffset, int32_t aAppUnitsPerDevPixel, float aXScale,
      float aYScale);

  void PaintItems(std::vector<AssignedDisplayItem>& aItems,
                  const nsIntRect& aRect, gfxContext* aContext,
                  nsDisplayListBuilder* aBuilder, nsPresContext* aPresContext,
                  const nsIntPoint& aOffset, float aXScale, float aYScale);

   * We accumulate ClippedDisplayItem elements in a hashtable during
   * the paint process. This is the hashentry for that hashtable.
   * Add the PaintedDisplayItemLayerUserData object as being used in this
   * transaction so that we clean it up afterwards.
  void AddPaintedLayerItemsEntry(PaintedDisplayItemLayerUserData* aData);

  PaintedLayerData* GetContainingPaintedLayerData() {
    return mContainingPaintedLayer;

  const DisplayItemClip* GetInactiveLayerClip() const {
    return mInactiveLayerClip;

   * If we're building layers for an item with an inactive layer tree,
   * this function saves the item's clip, which will later be applied
   * to the event regions. The clip should be relative to
   * mContainingPaintedLayer->mReferenceFrame.
  void SetInactiveLayerClip(const DisplayItemClip* aClip) {
    mInactiveLayerClip = aClip;

  bool IsBuildingRetainedLayers() {
    return !mIsInactiveLayerManager && mRetainingManager;

   * Attempt to build the most compressed layer tree possible, even if it means
   * throwing away existing retained buffers.
  void SetLayerTreeCompressionMode() { mInLayerTreeCompressionMode = true; }
  bool CheckInLayerTreeCompressionMode();

  void ComputeGeometryChangeForItem(DisplayItemData* aData);

   * The layer manager belonging to the widget that is being retained
   * across paints.
  LayerManager* mRetainingManager;
   * The root prescontext for the display list builder reference frame
  RefPtr<nsRootPresContext> mRootPresContext;

   * The display list builder being used.
  nsDisplayListBuilder* mDisplayListBuilder;
   * An array of PaintedLayer user data objects containing the
   * list of display items (plus clipping data) to be rendered in the
   * layer. We clean these up at the end of the transaction to
   * remove references to display items.
  AutoTArray<RefPtr<PaintedDisplayItemLayerUserData>, 5> mPaintedLayerItems;

   * When building layers for an inactive layer, this is where the
   * inactive layer will be placed.
  PaintedLayerData* mContainingPaintedLayer;

   * When building layers for an inactive layer, this stores the clip
   * of the display item that built the inactive layer.
  const DisplayItemClip* mInactiveLayerClip;

   * Indicates that the entire layer tree should be rerendered
   * during this paint.
  bool mInvalidateAllLayers;

  bool mInLayerTreeCompressionMode;

  bool mIsInactiveLayerManager;

}  // namespace mozilla