cc: Add a flag to layers that returns true if the layer is in RSLL.

cc/layers/layer_impl.cc

Index: cc/layers/layer_impl.cc
diff --git a/cc/layers/layer_impl.cc b/cc/layers/layer_impl.cc
index 855f43dc7b98a73ce724b17d0368310d9495f9cd..660dc49a03052c8576c34ce40ace1d8f6f5e989a 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -1502,6 +1502,11 @@ void LayerImpl::AsValueInto(base::DictionaryValue* state) const {
   }
 }
 
+bool LayerImpl::is_render_surface_list_member() const {
+  return draw_properties_.last_valid_render_surface_list_id ==
+         layer_tree_impl_->current_render_surface_list_id();
+}
+
 size_t LayerImpl::GPUMemoryUsageInBytes() const { return 0; }
 
 scoped_ptr<base::Value> LayerImpl::AsValue() const {