2D Canvas: disable rendering deferral in cases with a lot of overdraw

Source/platform/graphics/Canvas2DLayerBridge.h

 /*
  * Copyright (C) 2012 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.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 55 matching lines @@
     void willOverwriteCanvas();
     SkCanvas* canvas();
     void disableDeferral();
     bool checkSurfaceValid();
     bool restoreSurface();
     WebLayer* layer() const;
     bool isAccelerated() const { return true; }
     void setFilterQuality(SkFilterQuality);
     void setIsHidden(bool);
     void setImageBuffer(ImageBuffer*);
-    void didDraw();
+    void didDraw(const FloatRect&);
     bool writePixels(const SkImageInfo&, const void* pixels, size_t rowBytes, int x, int y);
     void flush();
     void flushGpu();
 
     void limitPendingFrames();
     bool isHidden() { return m_isHidden; }
 
     void beginDestruction();
 
     PassRefPtr<SkImage> newImageSnapshot();
@@ skipping 39 matching lines @@
     enum {
         // We should normally not have more that two active mailboxes at a time,
         // but sometime we may have three due to the async nature of mailbox handling.
         MaxActiveMailboxes = 3,
     };
 
     Deque<MailboxInfo, MaxActiveMailboxes> m_mailboxes;
     GLenum m_lastFilter;
     OpacityMode m_opacityMode;
     IntSize m_size;
+    int m_recordingPixelCount;
 };
 
 } // namespace blink
 
 #endif