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

Source/core/platform/graphics/GraphicsContext.h

Index: Source/core/platform/graphics/GraphicsContext.h
diff --git a/Source/core/platform/graphics/GraphicsContext.h b/Source/core/platform/graphics/GraphicsContext.h
index 0dc1fc52d60e4db81e6523296257278c041fec1b..3704769056e4eb7a8e77bf16f9812c2236beaa02 100644
--- a/Source/core/platform/graphics/GraphicsContext.h
+++ b/Source/core/platform/graphics/GraphicsContext.h
@@ -45,6 +45,7 @@
 
 class SkBitmap;
 class SkDevice;
+class SkImage;
 class SkPaint;
 class SkPath;
 class SkRRect;
@@ -239,6 +240,7 @@ public:
     void drawImage(Image*, const FloatRect& destRect);
     void drawImage(Image*, const FloatRect& destRect, const FloatRect& srcRect, CompositeOperator = CompositeSourceOver, RespectImageOrientationEnum = DoNotRespectImageOrientation, bool useLowQualityScale = false);
     void drawImage(Image*, const FloatRect& destRect, const FloatRect& srcRect, CompositeOperator, BlendMode, RespectImageOrientationEnum = DoNotRespectImageOrientation, bool useLowQualityScale = false);
+    void drawImage(SkImage*, const FloatRect& destRect, const FloatRect& srcRect, CompositeOperator = CompositeSourceOver, BlendMode = BlendModeNormal, bool useLowQualityScale = false);
 
     void drawTiledImage(Image*, const IntRect& destRect, const IntPoint& srcPoint, const IntSize& tileSize,
         CompositeOperator = CompositeSourceOver, bool useLowQualityScale = false, BlendMode = BlendModeNormal);