Add an heuristic for promoting canvases to GPU acceleration

third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.h

 /*
  * Copyright (C) 2006, 2007, 2009, 2010, 2011, 2012 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
@@ skipping 181 matching lines @@
   bool isAccelerationOptimalForCanvasContent() const;
 
   void resetUsageTracking();
 
   void incrementFrameCount() { m_usageCounters.numFramesSinceReset++; }
 
   bool isPaintable() const final { return hasImageBuffer(); }
 
   ColorBehavior drawImageColorBehavior() const final;
 
+  void willDrawImage(CanvasImageSource*) const final;
+
  private:
   friend class CanvasRenderingContext2DAutoRestoreSkCanvas;
 
   CanvasRenderingContext2D(HTMLCanvasElement*,
                            const CanvasContextCreationAttributes& attrs,
                            Document&);
 
   void dispose();
 
   void dispatchContextLostEvent(TimerBase*);
@@ skipping 49 matching lines @@
 
 DEFINE_TYPE_CASTS(CanvasRenderingContext2D,
                   CanvasRenderingContext,
                   context,
                   context->is2d() && context->canvas(),
                   context.is2d() && context.canvas());
 
 }  // namespace blink
 
 #endif  // CanvasRenderingContext2D_h