cc : Make tree synchronization independent of layer tree hierarchy (2)

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index b22de54fd21c0bf080023b2e712a8fbf3d812e18..bf706b6149cc5476cea675444c58ae1166c9fa3b 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -1974,13 +1974,7 @@ void LayerTreeHostImpl::ActivateSyncTree() {
         active_tree_->root_layer()->PushLayerPropertyChangedForSubtree();
     }
 
-    std::unordered_set<LayerImpl*> layers_that_should_push_properties =
-        pending_tree_->LayersThatShouldPushProperties();
-    for (auto pending_layer : layers_that_should_push_properties) {
-      LayerImpl* active_layer = active_tree_->LayerById(pending_layer->id());
-      DCHECK(active_layer);
-      pending_layer->PushPropertiesTo(active_layer);
-    }
+    TreeSynchronizer::PushLayerProperties(pending_tree(), active_tree());
     pending_tree_->PushPropertiesTo(active_tree_.get());
     if (pending_tree_->root_layer())
       pending_tree_->property_trees()->ResetAllChangeTracking(