CC Animation: Use ElementId to attach CC animation players.

ui/compositor/layer_animator.h

Index: ui/compositor/layer_animator.h
diff --git a/ui/compositor/layer_animator.h b/ui/compositor/layer_animator.h
index e07de31f9206f4863a7165f10d4a2ad3be7a7dda..81e124959bee8086b841756ce740ef69c2279b23 100644
--- a/ui/compositor/layer_animator.h
+++ b/ui/compositor/layer_animator.h
@@ -17,6 +17,7 @@
 #include "base/time/time.h"
 #include "cc/animation/animation_delegate.h"
 #include "cc/animation/target_property.h"
+#include "cc/trees/element_id.h"
 #include "ui/compositor/compositor_export.h"
 #include "ui/compositor/layer_animation_element.h"
 #include "ui/compositor/layer_threaded_animation_delegate.h"
@@ -362,8 +363,8 @@ class COMPOSITOR_EXPORT LayerAnimator
   void AddThreadedAnimation(std::unique_ptr<cc::Animation> animation) override;
   void RemoveThreadedAnimation(int animation_id) override;
 
-  void AttachLayerToAnimationPlayer(int layer_id);
-  void DetachLayerFromAnimationPlayer();
+  void AttachElementToAnimationPlayer(cc::ElementId element_id);
+  void DetachElementFromAnimationPlayer();
 
   // This is the queue of animations to run.
   AnimationQueue animation_queue_;