Use recomputed interest rect only if it changed enough

third_party/WebKit/Source/web/PageOverlay.h

 /*
  * Copyright (C) 2011 Google 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.
  *
@@ skipping 51 matching lines @@
 
     ~PageOverlay();
 
     void update();
 
     GraphicsLayer* graphicsLayer() const { return m_layer.get(); }
     DisplayItemClient displayItemClient() const { return toDisplayItemClient(this); }
     String debugName() const { return "PageOverlay"; }
 
     // GraphicsLayerClient implementation
-    void paintContents(const GraphicsLayer*, GraphicsContext&, GraphicsLayerPaintingPhase, const IntRect* inClip) const override;
-    String debugName(const GraphicsLayer*) override;
+    IntRect computeInterestRect(const GraphicsLayer*, const IntRect&) const override;
+    void paintContents(const GraphicsLayer*, GraphicsContext&, GraphicsLayerPaintingPhase, const IntRect& interestRect) const override;
+    String debugName(const GraphicsLayer*) const override;
 
 private:
     PageOverlay(WebViewImpl*, PageOverlay::Delegate*);
 
     WebViewImpl* m_viewImpl;
     Persistent<PageOverlay::Delegate> m_delegate;
     OwnPtr<GraphicsLayer> m_layer;
 };
 
 } // namespace blink
 
 #endif // PageOverlay_h