CC Animation: Let MutatorHostClient deals with elements instead of layers.

ui/compositor/layer_animator.cc

Index: ui/compositor/layer_animator.cc
diff --git a/ui/compositor/layer_animator.cc b/ui/compositor/layer_animator.cc
index 5df5949b2bd4f264c5b38b72c6b5b0e310dcc081..1defb3f8f06ef3c5cbeee748fd05be64061fa8f3 100644
--- a/ui/compositor/layer_animator.cc
+++ b/ui/compositor/layer_animator.cc
@@ -182,7 +182,7 @@ void LayerAnimator::ResetCompositor(Compositor* compositor) {
   // so it may be picked up in LayerAnimator::SetCompositor.
   if (layer_id) {
     element_animations_state_ =
-        timeline->animation_host()->GetElementAnimationsForLayerId(layer_id);
+        timeline->animation_host()->GetElementAnimationsForElementId(layer_id);
   }
 
   DetachLayerFromAnimationPlayer();