Make 2D canvas smarter about chosing whether or not to use GPU acceleration

Source/platform/graphics/ImageBuffer.h

Index: Source/platform/graphics/ImageBuffer.h
diff --git a/Source/platform/graphics/ImageBuffer.h b/Source/platform/graphics/ImageBuffer.h
index 30ef58220895362c18aa865202fdd2b1d399e1f4..0de74a87d117259c620e4ddf945649a2ee47fed2 100644
--- a/Source/platform/graphics/ImageBuffer.h
+++ b/Source/platform/graphics/ImageBuffer.h
@@ -82,6 +82,7 @@ public:
     bool isRecording() const { return m_surface->isRecording(); }
     void setHasExpensiveOp() { m_surface->setHasExpensiveOp(); }
     bool isExpensiveToPaint() const { return m_surface->isExpensiveToPaint(); }
+    void prepareSurfaceForPaintingIfNeeded() { m_surface->prepareSurfaceForPaintingIfNeeded(); }
     bool isSurfaceValid() const;
     bool restoreSurface() const;
     void didDraw(const FloatRect&) const;
@@ -130,8 +131,8 @@ public:
 
     void notifySurfaceInvalid();
 
-    PassRefPtr<SkImage> newSkImageSnapshot() const;
-    PassRefPtr<Image> newImageSnapshot() const;
+    PassRefPtr<SkImage> newSkImageSnapshot(AccelerationHint) const;
+    PassRefPtr<Image> newImageSnapshot(AccelerationHint = PreferNoAcceleration) const;
 
     DisplayItemClient displayItemClient() const { return toDisplayItemClient(this); }
     String debugName() const { return "ImageBuffer"; }