compositor-worker: plumb element id and mutable properties

cc/layers/layer.h

Index: cc/layers/layer.h
diff --git a/cc/layers/layer.h b/cc/layers/layer.h
index c4c490c582270c5efcbced254b5caf5f79cd1fd7..a64e04e16a81bdece430b2d816b52e0029319db0 100644
--- a/cc/layers/layer.h
+++ b/cc/layers/layer.h
@@ -546,6 +546,12 @@ class CC_EXPORT Layer : public base::RefCounted<Layer>,
     return num_layer_or_descendants_with_copy_request_;
   }
 
+  void SetElementId(uint64_t id);
+  uint64_t element_id() const { return element_id_; }
+
+  void SetMutableProperties(uint32_t properties);
+  uint32_t mutable_properties() const { return mutable_properties_; }
+
   void set_visited(bool visited);
   bool visited();
   void set_layer_or_descendant_is_drawn(bool layer_or_descendant_is_drawn);
@@ -707,6 +713,8 @@ class CC_EXPORT Layer : public base::RefCounted<Layer>,
   int clip_tree_index_;
   int property_tree_sequence_number_;
   int num_layer_or_descendants_with_copy_request_;
+  uint64_t element_id_;
+  uint32_t mutable_properties_;
   gfx::Vector2dF offset_to_transform_parent_;
   bool should_flatten_transform_from_property_tree_ : 1;
   bool should_scroll_on_main_thread_ : 1;