Animations: Introduce compositor AnimationPlayer and AnimationTimeline.

public/platform/WebCompositorSupport.h

Index: public/platform/WebCompositorSupport.h
diff --git a/public/platform/WebCompositorSupport.h b/public/platform/WebCompositorSupport.h
index 76fc67c8ffc897652321ea83c0d2999e6e262bf8..3c3c74a77fbbaa9863e571a6ce7dd13923eb4b31 100644
--- a/public/platform/WebCompositorSupport.h
+++ b/public/platform/WebCompositorSupport.h
@@ -39,6 +39,8 @@
 namespace blink {
 
 class WebCompositorAnimationCurve;
+class WebCompositorAnimationPlayer;
+class WebCompositorAnimationTimeline;
 class WebCompositorOutputSurface;
 class WebContentLayer;
 class WebContentLayerClient;
@@ -103,6 +105,10 @@ public:
 
     virtual WebFilterOperations* createFilterOperations() { return 0; }
 
+    virtual WebCompositorAnimationPlayer* createAnimationPlayer() { return 0; }
+
+    virtual WebCompositorAnimationTimeline* createAnimationTimeline() { return 0; }
+
 protected:
     virtual ~WebCompositorSupport() { }
 };