Making display list canvases fall back to gpu-accelerated when appropriate

Source/core/html/HTMLCanvasElement.h

Index: Source/core/html/HTMLCanvasElement.h
diff --git a/Source/core/html/HTMLCanvasElement.h b/Source/core/html/HTMLCanvasElement.h
index 85f683b8edb850fddec1aaba5da3e80fb291e617..a2be58c4a29282968ea828924774c3ad7ae71ce3 100644
--- a/Source/core/html/HTMLCanvasElement.h
+++ b/Source/core/html/HTMLCanvasElement.h
@@ -55,6 +55,7 @@ class ImageData;
 class ImageBuffer;
 class ImageBufferSurface;
 class IntSize;
+class RecordingImageBufferFallbackSurfaceFactory;
 
 class CanvasObserver : public WillBeGarbageCollectedMixin {
     DECLARE_EMPTY_VIRTUAL_DESTRUCTOR_WILL_BE_REMOVED(CanvasObserver);
@@ -174,6 +175,7 @@ private:
 
     void reset();
 
+    PassOwnPtr<RecordingImageBufferFallbackSurfaceFactory> createSurfaceFactory(const IntSize& deviceSize, int* msaaSampleCount) const;
     PassOwnPtr<ImageBufferSurface> createImageBufferSurface(const IntSize& deviceSize, int* msaaSampleCount);
     void createImageBuffer();
     void createImageBufferInternal();