Use recomputed interest rect only if it changed enough

third_party/WebKit/Source/core/frame/VisualViewport.h

 /*
  * Copyright (C) 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 192 matching lines @@
     // Heuristic-based function for determining if we should disable workarounds
     // for viewing websites that are not optimized for mobile devices.
     bool shouldDisableDesktopWorkarounds() const;
 
 private:
     explicit VisualViewport(FrameHost&);
 
     bool visualViewportSuppliesScrollbars() const;
 
     // GraphicsLayerClient implementation.
-    void paintContents(const GraphicsLayer*, GraphicsContext&, GraphicsLayerPaintingPhase, const IntRect* inClip) const override;
+    IntRect paintContents(const GraphicsLayer*, GraphicsContext&, GraphicsLayerPaintingPhase, const IntRect*) const override;
     String debugName(const GraphicsLayer*) override;
 
     void setupScrollbar(WebScrollbar::Orientation);
     FloatPoint clampOffsetToBoundaries(const FloatPoint&);
 
     LocalFrame* mainFrame() const;
 
     FrameHost& frameHost() const
     {
         ASSERT(m_frameHost);
@@ skipping 16 matching lines @@
     float m_scale;
     IntSize m_size;
     float m_topControlsAdjustment;
     float m_maxPageScale;
     bool m_trackPinchZoomStatsForPage;
 };
 
 } // namespace blink
 
 #endif // VisualViewport_h