Eliminate deferral overhead with canvas to canvas draws

Source/platform/graphics/ImageBufferSurface.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 40 matching lines @@
 class ImageBuffer;
 class WebLayer;
 class FloatRect;
 class GraphicsContext;
 
 class PLATFORM_EXPORT ImageBufferSurface {
     WTF_MAKE_NONCOPYABLE(ImageBufferSurface); WTF_MAKE_FAST_ALLOCATED(ImageBufferSurface);
 public:
     virtual ~ImageBufferSurface();
 
-    virtual SkCanvas* canvas() { return immediateCanvas(); }
-    virtual SkCanvas* immediateCanvas() = 0;
+    virtual SkCanvas* canvas() = 0;
+    virtual void disableDeferral() { }
     virtual const SkBitmap& deprecatedBitmapForOverwrite();
     virtual void willOverwriteCanvas() { }
     virtual void didDraw(const FloatRect& rect) { }
     virtual bool isValid() const = 0;
     virtual bool restore() { return false; }
     virtual WebLayer* layer() const { return 0; }
     virtual bool isAccelerated() const { return false; }
     virtual bool isRecording() const { return false; }
     virtual bool isExpensiveToPaint() { return false; }
     virtual void setFilterQuality(SkFilterQuality) { }
@@ skipping 20 matching lines @@
     void clear();
 
 private:
     OpacityMode m_opacityMode;
     IntSize m_size;
 };
 
 } // namespace blink
 
 #endif