Initial implementation of display list backed 2D canvases

Source/platform/graphics/skia/OpaqueRegionSkia.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:
  *
  *     * 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 66 matching lines @@
         SkPaint paint;
 
         // An image mask is being applied to the layer.
         bool hasImageMask;
         // The opaque area in the image mask.
         SkRect imageOpaqueRect;
 
         SkRect opaqueRect;
     };
 
+    void reset();
+
 private:
     void didDraw(const GraphicsContext*, const SkRect&, const SkPaint&, const SkBitmap* sourceBitmap, bool fillsBounds, DrawType);
     void applyOpaqueRegionFromLayer(const GraphicsContext*, const SkRect& layerOpaqueRect, const SkPaint&);
     void markRectAsOpaque(const SkRect&);
     void markRectAsNonOpaque(const SkRect&);
     void markAllAsNonOpaque();
 
     SkRect& currentTrackingOpaqueRect();
 
     SkRect m_opaqueRect;
 
     Vector<CanvasLayerState, 3> m_canvasLayerStack;
 };
 
 }
 #endif // OpaqueRegionSkia_h