Implement interest rects for synchronized paint.

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

 /*
  * Copyright (C) 2009 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 163 matching lines @@
     void updateDirectCompositingReasons(PaintLayer*);
 
     bool inOverlayFullscreenVideo() const { return m_inOverlayFullscreenVideo; }
 
 private:
 #if ENABLE(ASSERT)
     void assertNoUnresolvedDirtyBits();
 #endif
 
     // GraphicsLayerClient implementation
+    void paintContentsIfNeeded(const GraphicsLayer*, GraphicsContext&, GraphicsLayerPaintingPhase) const override;
     void paintContents(const GraphicsLayer*, GraphicsContext&, GraphicsLayerPaintingPhase, const IntRect&) const override;
 
     bool isTrackingPaintInvalidations() const override;
 
     void updateWithoutAcceleratedCompositing(CompositingUpdateType);
     void updateIfNeeded();
 
     void ensureRootLayer();
     void destroyRootLayer();
 
@@ skipping 53 matching lines @@
 
     // Layers for overflow controls
     OwnPtr<GraphicsLayer> m_layerForHorizontalScrollbar;
     OwnPtr<GraphicsLayer> m_layerForVerticalScrollbar;
     OwnPtr<GraphicsLayer> m_layerForScrollCorner;
 };
 
 } // namespace blink
 
 #endif // PaintLayerCompositor_h