Always use the WebFrameWidget when attaching the root graphics

third_party/WebKit/public/web/WebFrameWidget.h

Index: third_party/WebKit/public/web/WebFrameWidget.h
diff --git a/third_party/WebKit/public/web/WebFrameWidget.h b/third_party/WebKit/public/web/WebFrameWidget.h
index d856c943f88e1c4a7d22b767b74269065fbd79e4..10d150591e54bd30d7d7a660a90fb507cd57e1f3 100644
--- a/third_party/WebKit/public/web/WebFrameWidget.h
+++ b/third_party/WebKit/public/web/WebFrameWidget.h
@@ -37,7 +37,9 @@
 
 namespace blink {
 
+class CompositorAnimationTimeline;
 class CompositorProxyClient;
+class GraphicsLayer;
 class WebLocalFrame;
 class WebView;
 class WebWidgetClient;
@@ -71,6 +73,8 @@ public:
     // first call to this method.
     virtual void setBaseBackgroundColor(WebColor) = 0;
 
+
+    // Blink internal methods --------------------------------------------------
     // TODO(dcheng): Temporary: there should only be one WebFrameWidget
     // implementation but the Blink API is currently in a transition state.
     // See https://goo.gl/7yVrnb. These methods should only be used inside
@@ -79,6 +83,14 @@ public:
     virtual void scheduleAnimation() = 0;
     virtual CompositorProxyClient* createCompositorProxyClient() = 0;
     virtual WebWidgetClient* client() const = 0;
+
+    // Sets the root graphics layer. |GraphicsLayer| can be null when detaching
+    // the root layer.
+    virtual void setRootGraphicsLayer(GraphicsLayer*) = 0;
+
+    // Attaches/detaches a CompositorAnimationTimeline to the layer tree.
+    virtual void attachCompositorAnimationTimeline(CompositorAnimationTimeline*) = 0;
+    virtual void detachCompositorAnimationTimeline(CompositorAnimationTimeline*) = 0;
 };
 
 } // namespace blink