Blink Compositor Animation: Introduce CompositorAnimationHost correctly.

third_party/WebKit/Source/web/WebFrameWidgetImpl.h

Index: third_party/WebKit/Source/web/WebFrameWidgetImpl.h
diff --git a/third_party/WebKit/Source/web/WebFrameWidgetImpl.h b/third_party/WebKit/Source/web/WebFrameWidgetImpl.h
index 38148a15914faee3c566e737ef234d69b8dcaa2a..efda4edcaf871f0be62df26441cd7b6d3689d8dc 100644
--- a/third_party/WebKit/Source/web/WebFrameWidgetImpl.h
+++ b/third_party/WebKit/Source/web/WebFrameWidgetImpl.h
@@ -47,6 +47,8 @@
 #include "wtf/HashSet.h"
 
 namespace blink {
+
+class CompositorAnimationHost;
 class Frame;
 class Element;
 class InspectorOverlay;
@@ -218,6 +220,7 @@ class WebFrameWidgetImpl final
   WebLayerTreeView* m_layerTreeView;
   WebLayer* m_rootLayer;
   GraphicsLayer* m_rootGraphicsLayer;
+  std::unique_ptr<CompositorAnimationHost> m_compositorAnimationHost;
   bool m_isAcceleratedCompositingActive;
   bool m_layerTreeViewClosed;