Fix subpixel accumulation for composited content layers

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 286 matching lines @@
 
     // Returns true if this layer has content that needs to be displayed by painting into the backing store.
     bool containsPaintedContent() const;
     // Returns true if the Layer just contains an image that we can composite directly.
     bool isDirectlyCompositedImage() const;
     void updateImageContents();
 
     Color layoutObjectBackgroundColor() const;
     void updateBackgroundColor();
     void updateContentsRect();
-    void updateContentsOffsetInCompositingLayer(const IntPoint& snappedOffsetFromCompositedAncestor, const IntPoint& graphicsLayerParentLocation);
     void updateAfterPartResize();
     void updateCompositingReasons();
 
     static bool hasVisibleNonCompositingDescendant(PaintLayer* parent);
 
     void doPaintTask(const GraphicsLayerPaintInfo&, const GraphicsLayer&, const PaintLayerFlags&, GraphicsContext&, const IntRect& clip) const;
 
     // 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.
@@ skipping 117 matching lines @@
     //
     // Stacking children of a squashed layer receive graphics layers that are parented to the compositd ancestor of the
     // squashed layer (i.e. nearest enclosing composited layer that is not squashed).
     std::unique_ptr<GraphicsLayer> m_squashingContainmentLayer; // Only used if any squashed layers exist and m_squashingContainmentLayer is not present, to contain the squashed layers as siblings to the rest of the GraphicsLayer tree chunk.
     std::unique_ptr<GraphicsLayer> m_squashingLayer; // Only used if any squashed layers exist, this is the backing that squashed layers paint into.
     Vector<GraphicsLayerPaintInfo> m_squashedLayers;
     LayoutPoint m_squashingLayerOffsetFromTransformedAncestor;
 
     LayoutRect m_compositedBounds;
 
-    LayoutSize m_contentOffsetInCompositingLayer;
-
     // We keep track of the scrolling contents offset, so that when it changes we can notify the ScrollingCoordinator, which
     // passes on main-thread scrolling updates to the compositor.
     DoubleSize m_scrollingContentsOffset;
 
-    unsigned m_contentOffsetInCompositingLayerDirty : 1;
-
     unsigned m_pendingUpdateScope : 2;
     unsigned m_isMainFrameLayoutViewLayer : 1;
 
     unsigned m_backgroundLayerPaintsFixedRootBackground : 1;
     unsigned m_scrollingContentsAreEmpty : 1;
 
     friend class CompositedLayerMappingTest;
 };
 
 } // namespace blink
 
 #endif // CompositedLayerMapping_h