Blink Compositor Animation: Introduce CompositorAnimationHost correctly.

third_party/WebKit/Source/core/frame/VisualViewport.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 777 matching lines @@
   //    the initial viewport width.
   // 2. The author has disabled viewport zoom.
   const PageScaleConstraints& constraints =
       frameHost().pageScaleConstraintsSet().pageDefinedConstraints();
 
   return mainFrame()->view()->layoutSize().width() == m_size.width() ||
          (constraints.minimumScale == constraints.maximumScale &&
           constraints.minimumScale != -1);
 }
 
+CompositorAnimationHost* VisualViewport::compositorAnimationHost() const {
+  ScrollingCoordinator* c = frameHost().page().scrollingCoordinator();
+  return c ? c->compositorAnimationHost() : nullptr;
+}
+
 CompositorAnimationTimeline* VisualViewport::compositorAnimationTimeline()
     const {
   ScrollingCoordinator* c = frameHost().page().scrollingCoordinator();
   return c ? c->compositorAnimationTimeline() : nullptr;
 }
 
 void VisualViewport::notifyRootFrameViewport() const {
   if (!mainFrame() || !mainFrame()->view())
     return;
 
@@ skipping 23 matching lines @@
   } else if (graphicsLayer == m_rootTransformLayer.get()) {
     name = "Root Transform Layer";
   } else {
     ASSERT_NOT_REACHED();
   }
 
   return name;
 }
 
 }  // namespace blink