Change cc::ElementId to be a uint64_t

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 feb3e5ae06de9376ff142d13b137263d7c505911..d143fbafac09918f88937d87cfe4af296148ad1d 100644
--- a/cc/trees/layer_tree_impl.h
+++ b/cc/trees/layer_tree_impl.h
@@ -517,13 +517,12 @@ class CC_EXPORT LayerTreeImpl {
   // Set of layers that need to push properties.
   std::unordered_set<LayerImpl*> layers_that_should_push_properties_;
 
-  std::unordered_map<ElementId, int, ElementIdHash> element_layers_map_;
+  std::unordered_map<ElementId, int> element_layers_map_;
 
-  std::unordered_map<ElementId, float, ElementIdHash>
-      element_id_to_opacity_animations_;
-  std::unordered_map<ElementId, gfx::Transform, ElementIdHash>
+  std::unordered_map<ElementId, float> element_id_to_opacity_animations_;
+  std::unordered_map<ElementId, gfx::Transform>
       element_id_to_transform_animations_;
-  std::unordered_map<ElementId, FilterOperations, ElementIdHash>
+  std::unordered_map<ElementId, FilterOperations>
       element_id_to_filter_animations_;
 
   // Maps from clip layer ids to scroll layer ids.  Note that this only includes