Put rare PaintLayer fields into PaintLayerRareData

third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h

 /*
  * Copyright (C) 2009, 2010, 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 43 matching lines @@
 
     GraphicsLayerPaintInfo() : paintLayer(nullptr), offsetFromLayoutObjectSet(false) { }
 };
 
 enum GraphicsLayerUpdateScope {
     GraphicsLayerUpdateNone,
     GraphicsLayerUpdateLocal,
     GraphicsLayerUpdateSubtree,
 };
 
-// CompositedLayerMapping keeps track of how Layers of the layout tree correspond to
+// CompositedLayerMapping keeps track of how PaintLayers correspond to
 // GraphicsLayers of the composited layer tree. Each instance of CompositedLayerMapping
 // manages a small cluster of GraphicsLayers and the references to which Layers
 // and paint phases contribute to each GraphicsLayer.
 //
-// Currently (Oct. 2013) there is one CompositedLayerMapping for each Layer,
-// but this is likely to evolve soon.
+// - If a PaintLayer is composited,
+//   - if it paints into its own backings (GraphicsLayers), it owns a
+//     CompositedLayerMapping (PaintLayer::compositedLayerMapping()) to keep
+//     track the backings;
+//   - if it paints into grouped backing (i.e. it's squashed), it has a pointer
+//     (PaintLayer::groupedMapping()) to the CompositedLayerMapping into which
+//     the layer is squashed;

[chrishtr, 2016/01/28 18:04:29]

s/layer/PaintLayer/

[Xianzhu, 2016/01/28 18:30:30]

Done.

+// - Otherwise the layer doesn't own or directly reference any CompositedLayerMapping.

[chrishtr, 2016/01/28 18:04:29]

s/layer/PaintLayer/

[Xianzhu, 2016/01/28 18:30:30]

Done.

 class CORE_EXPORT CompositedLayerMapping final : public GraphicsLayerClient {
 
     WTF_MAKE_NONCOPYABLE(CompositedLayerMapping); USING_FAST_MALLOC(CompositedLayerMapping);
 public:
     explicit CompositedLayerMapping(PaintLayer&);
     ~CompositedLayerMapping() override;
 
     PaintLayer& owningLayer() const { return m_owningLayer; }
 
     bool updateGraphicsLayerConfiguration();
@@ skipping 165 matching lines @@
     bool updateChildTransformLayer(bool needsChildTransformLayer);
     bool updateOverflowControlsLayers(bool needsHorizontalScrollbarLayer, bool needsVerticalScrollbarLayer, bool needsScrollCornerLayer, bool needsAncestorClip);
     bool updateForegroundLayer(bool needsForegroundLayer);
     bool updateBackgroundLayer(bool needsBackgroundLayer);
     bool updateMaskLayer(bool needsMaskLayer);
     void updateChildClippingMaskLayer(bool needsChildClippingMaskLayer);
     bool requiresHorizontalScrollbarLayer() const { return m_owningLayer.scrollableArea() && m_owningLayer.scrollableArea()->horizontalScrollbar(); }
     bool requiresVerticalScrollbarLayer() const { return m_owningLayer.scrollableArea() && m_owningLayer.scrollableArea()->verticalScrollbar(); }
     bool requiresScrollCornerLayer() const { return m_owningLayer.scrollableArea() && !m_owningLayer.scrollableArea()->scrollCornerAndResizerRect().isEmpty(); }
     bool updateScrollingLayers(bool scrollingLayers);
-    void updateScrollParent(PaintLayer*);
-    void updateClipParent(PaintLayer* scrollParent);
+    void updateScrollParent(const PaintLayer*);
+    void updateClipParent(const PaintLayer* scrollParent);
     bool updateSquashingLayers(bool needsSquashingLayers);
     void updateDrawsContent();
     void updateChildrenTransform();
     void updateCompositedBounds();
     void registerScrollingLayers();
 
     // Also sets subpixelAccumulation on the layer.
     void computeBoundsOfOwningLayer(const PaintLayer* compositedAncestor, IntRect& localCompositingBounds, IntRect& compositingBoundsRelativeToCompositedAncestor, LayoutPoint& offsetFromCompositedAncestor, IntPoint& snappedOffsetFromCompositedAncestor);
 
     void setBackgroundLayerPaintsFixedRootBackground(bool);
@@ skipping 31 matching lines @@
 
     // Computes the background clip rect for the given squashed layer, up to any containing layer that is squashed into the
     // same squashing layer and contains this squashed layer's clipping ancestor.
     // The clip rect is returned in the coordinate space of the given squashed layer.
     // If there is no such containing layer, returns the infinite rect.
     // FIXME: unify this code with the code that sets up m_ancestorClippingLayer. They are doing very similar things.
     static IntRect localClipRectForSquashedLayer(const PaintLayer& referenceLayer, const GraphicsLayerPaintInfo&,  const Vector<GraphicsLayerPaintInfo>& layers);
 
     // Return true if |m_owningLayer|'s compositing ancestor is not a descendant (inclusive) of the
     // clipping container for |m_owningLayer|.
-    bool owningLayerClippedByLayerNotAboveCompositedAncestor(PaintLayer* scrollParent);
+    bool owningLayerClippedByLayerNotAboveCompositedAncestor(const PaintLayer* scrollParent);
 
-    PaintLayer* scrollParent();
+    const PaintLayer* scrollParent();
 
     // Clear the groupedMapping entry on the layer at the given index, only if that layer does
     // not appear earlier in the set of layers for this object.
     bool invalidateLayerIfNoPrecedingEntry(size_t);
 
     PaintLayer& m_owningLayer;
 
     // The hierarchy of layers that is maintained by the CompositedLayerMapping looks like this:
     //
     //  + m_ancestorClippingLayer [OPTIONAL]
@@ skipping 115 matching lines @@
 
     unsigned m_backgroundLayerPaintsFixedRootBackground : 1;
     unsigned m_scrollingContentsAreEmpty : 1;
 
     friend class CompositedLayerMappingTest;
 };
 
 } // namespace blink
 
 #endif // CompositedLayerMapping_h