Initial implementation of display list backed 2D canvases

Source/platform/graphics/GraphicsContext.h

Index: Source/platform/graphics/GraphicsContext.h
diff --git a/Source/platform/graphics/GraphicsContext.h b/Source/platform/graphics/GraphicsContext.h
index 1593a96cd6c836e939e9f9f93bad9bbc09b4f15e..a6a8783a99c090efb7207783413aac66b16cc462 100644
--- a/Source/platform/graphics/GraphicsContext.h
+++ b/Source/platform/graphics/GraphicsContext.h
@@ -95,6 +95,9 @@ public:
         ASSERT(!paintingDisabled());
         return m_canvas;
     }
+
+    void resetCanvas(SkCanvas*);
+
     bool paintingDisabled() const { return m_disabledState & PaintingDisabled; }
     bool contextDisabled() const { return m_disabledState; }
 
@@ -291,6 +294,8 @@ public:
 
     void drawImageBuffer(ImageBuffer*, const FloatRect& destRect, const FloatRect* srcRect = 0, CompositeOperator = CompositeSourceOver);
 
+    void drawPicture(PassRefPtr<SkPicture>, const FloatRect& dest, const FloatRect& src, CompositeOperator, blink::WebBlendMode);
+
     // These methods write to the canvas and modify the opaque region, if tracked.
     // Also drawLine(const IntPoint& point1, const IntPoint& point2) and fillRoundedRect
     void writePixels(const SkImageInfo&, const void* pixels, size_t rowBytes, int x, int y);