cc : Store surface layer ids on LayerTreeHost and push them at commit

cc/trees/tree_synchronizer.cc

Index: cc/trees/tree_synchronizer.cc
diff --git a/cc/trees/tree_synchronizer.cc b/cc/trees/tree_synchronizer.cc
index 87efee06cab3859b3382d1fbd7e7c8d6e07037b5..02c5250d0392274aaca2a6dd710f2b5f5b128b49 100644
--- a/cc/trees/tree_synchronizer.cc
+++ b/cc/trees/tree_synchronizer.cc
@@ -132,12 +132,24 @@ void TreeSynchronizer::PushLayerProperties(LayerTreeImpl* pending_tree,
                                            LayerTreeImpl* active_tree) {
   PushLayerPropertiesInternal(pending_tree->LayersThatShouldPushProperties(),
                               active_tree);
+  if (pending_tree->needs_surface_ids_sync()) {
+    active_tree->ClearSurfaceLayerIds();
+    active_tree->SetSurfaceLayerIds(pending_tree->SurfaceLayerIds());
+    // Reset for next update
+    pending_tree->set_needs_surface_ids_sync(false);
+  }
 }
 
 void TreeSynchronizer::PushLayerProperties(LayerTreeHost* host_tree,
                                            LayerTreeImpl* impl_tree) {
   PushLayerPropertiesInternal(host_tree->LayersThatShouldPushProperties(),
                               impl_tree);
+  if (host_tree->needs_surface_ids_sync()) {
+    impl_tree->ClearSurfaceLayerIds();
+    impl_tree->SetSurfaceLayerIds(host_tree->SurfaceLayerIds());
+    // Reset for next update
+    host_tree->set_needs_surface_ids_sync(false);
+  }
 }
 
 }  // namespace cc