Reland: Make 2D canvas disable gpu acceleration when getImageData is called

third_party/WebKit/Source/platform/graphics/ImageBufferClient.h

Index: third_party/WebKit/Source/platform/graphics/ImageBufferClient.h
diff --git a/third_party/WebKit/Source/platform/graphics/ImageBufferClient.h b/third_party/WebKit/Source/platform/graphics/ImageBufferClient.h
index 18f73c49134ceffe2fd848d04d8ddb8025e4beaf..69d1b1de980c9f1f550858f66318abe1ee1d001f 100644
--- a/third_party/WebKit/Source/platform/graphics/ImageBufferClient.h
+++ b/third_party/WebKit/Source/platform/graphics/ImageBufferClient.h
@@ -42,6 +42,7 @@ public:
     virtual ~ImageBufferClient() { }
     virtual void notifySurfaceInvalid() = 0;
     virtual bool isDirty() = 0;
+    virtual void didDisableAcceleration() = 0;
     virtual void didFinalizeFrame() = 0;
     virtual void restoreCanvasMatrixClipStack(SkCanvas*) const = 0;
 };