CC Animations: Make LayerAnimationController creation optional

ui/compositor/layer.h

Index: ui/compositor/layer.h
diff --git a/ui/compositor/layer.h b/ui/compositor/layer.h
index 3dbd1733b0b2982eacc194383e25f1dcc12a441e..fa6bd7b72868ace2520e2290ea6c7d5a19dfacce 100644
--- a/ui/compositor/layer.h
+++ b/ui/compositor/layer.h
@@ -413,6 +413,10 @@ class COMPOSITOR_EXPORT Layer
   // Creates a corresponding composited layer for |type_|.
   void CreateCcLayer();
 
+  void RegisterForAnimations(Compositor* compositor);
+  void AttachObservers();
+  void DetachObservers();
+
   // Recomputes and sets to |cc_layer_|.
   void RecomputeDrawsContentAndUVRect();
   void RecomputePosition();