Use SkImage as a backing store for copying 2d Contexts to ImageBitmaps.

Source/core/platform/graphics/ImageBuffer.h

Index: Source/core/platform/graphics/ImageBuffer.h
diff --git a/Source/core/platform/graphics/ImageBuffer.h b/Source/core/platform/graphics/ImageBuffer.h
index b4c0af9f3398dd1bf1c444c0504560a68ecf1f4a..32c7b0a34b0234185cdcccc09aedece2281691ac 100644
--- a/Source/core/platform/graphics/ImageBuffer.h
+++ b/Source/core/platform/graphics/ImageBuffer.h
@@ -43,6 +43,7 @@
 #include "wtf/Vector.h"
 
 class SkCanvas;
+class SkSurface;
 
 namespace WebKit { class WebLayer; }
 
@@ -104,6 +105,7 @@ public:
 
     GraphicsContext* context() const;
 
+    PassRefPtr<Image> imageSnapshot() const;
     PassRefPtr<Image> copyImage(BackingStoreCopy = CopyBackingStore, ScaleBehavior = Scaled) const;
     // Give hints on the faster copyImage Mode, return DontCopyBackingStore if it supports the DontCopyBackingStore behavior
     // or return CopyBackingStore if it doesn't.
@@ -132,6 +134,8 @@ public:
 
 private:
     bool isValid() const;
+    void createAcceleratedCanvas(const IntSize&, OwnPtr<Canvas2DLayerBridge>*, OpacityMode);
+    void createNonPlatformCanvas(const IntSize&);
 
     void draw(GraphicsContext*, const FloatRect&, const FloatRect& = FloatRect(0, 0, -1, -1), CompositeOperator = CompositeSourceOver, BlendMode = BlendModeNormal, bool useLowQualityScale = false);
     void drawPattern(GraphicsContext*, const FloatRect&, const FloatSize&, const FloatPoint&, CompositeOperator, const FloatRect&, BlendMode);
@@ -145,6 +149,7 @@ private:
     IntSize m_logicalSize;
     float m_resolutionScale;
     OwnPtr<SkCanvas> m_canvas;
+    OwnPtr<SkSurface> m_surface;
     OwnPtr<GraphicsContext> m_context;
     OwnPtr<Canvas2DLayerBridge> m_layerBridge;