[DRAFT] Animations: Profile hash look-ups for external mutators

cc/trees/layer_tree_impl.h

Index: cc/trees/layer_tree_impl.h
diff --git a/cc/trees/layer_tree_impl.h b/cc/trees/layer_tree_impl.h
index 527819ecf73013c5d8ccc717e299a79acaebf35c..3511130588ecde68c376290d6043a0019b45ca1a 100644
--- a/cc/trees/layer_tree_impl.h
+++ b/cc/trees/layer_tree_impl.h
@@ -250,6 +250,11 @@ class CC_EXPORT LayerTreeImpl {
   void RegisterLayer(LayerImpl* layer);
   void UnregisterLayer(LayerImpl* layer);
 
+  base::TimeDelta find_layer_by_id_stats() const {
+    return find_layer_by_id_stats_;
+  }
+  void ClearStatsOnFrameEnd();
+
   size_t NumLayers();
 
   AnimationRegistrar* GetAnimationRegistrar() const;
@@ -413,6 +418,7 @@ class CC_EXPORT LayerTreeImpl {
 
   typedef base::hash_map<int, LayerImpl*> LayerIdMap;
   LayerIdMap layer_id_map_;
+  mutable base::TimeDelta find_layer_by_id_stats_;
 
   std::vector<PictureLayerImpl*> picture_layers_;
   std::vector<LayerImpl*> layers_with_copy_output_request_;