Blink Compositor Animation: Introduce CompositorAnimationHost correctly.

third_party/WebKit/public/platform/WebLayerTreeView.h

Index: third_party/WebKit/public/platform/WebLayerTreeView.h
diff --git a/third_party/WebKit/public/platform/WebLayerTreeView.h b/third_party/WebKit/public/platform/WebLayerTreeView.h
index 6550def8626b90ad25b46f65984c9ec12b66554d..e2919800eed802e5f2de25b2d2fca72547a4750c 100644
--- a/third_party/WebKit/public/platform/WebLayerTreeView.h
+++ b/third_party/WebKit/public/platform/WebLayerTreeView.h
@@ -35,7 +35,7 @@
 #include "WebSize.h"
 
 namespace cc {
-class AnimationTimeline;
+class AnimationHost;
 }
 
 namespace blink {
@@ -56,9 +56,8 @@ class WebLayerTreeView {
   virtual void setRootLayer(const WebLayer&) {}
   virtual void clearRootLayer() {}
 
-  // TODO(loyso): These should use CompositorAnimationTimeline. crbug.com/584551
-  virtual void attachCompositorAnimationTimeline(cc::AnimationTimeline*) {}
-  virtual void detachCompositorAnimationTimeline(cc::AnimationTimeline*) {}
+  // TODO(loyso): This should use CompositorAnimationHost. crbug.com/584551
+  virtual cc::AnimationHost* compositorAnimationHost() { return nullptr; }
 
   // View properties ---------------------------------------------------