cc : Stop pushing layers from hidden subtrees 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 52f1bb384c752137b6ca7f2bfc72139e4bc42ad1..30502a9daf0e1803fe142353dc92ed48b56fcd37 100644
--- a/cc/trees/tree_synchronizer.cc
+++ b/cc/trees/tree_synchronizer.cc
@@ -74,17 +74,36 @@ std::unique_ptr<LayerImpl> ReuseOrCreateLayerImpl(OwnedLayerImplMap* old_layers,
   return layer_impl;
 }
 
+static bool IsHidden(Layer* layer) {
+  return layer->is_hidden();
+}
+
+static bool IsHidden(LayerImpl* layer) {
+  return false;
+}
+
+static void RemoveLayerShouldPushProperties(LayerTreeHost* host, Layer* layer) {
+  host->RemoveLayerShouldPushProperties(layer);
+}
+
+static void RemoveLayerShouldPushProperties(LayerTreeImpl* host_impl,
+                                            LayerImpl* layer) {}
+
 template <typename LayerTreeType>
 void PushLayerList(OwnedLayerImplMap* old_layers,
                    LayerTreeType* host,
                    LayerTreeImpl* tree_impl) {
   tree_impl->ClearLayerList();
   for (auto* layer : *host) {
-    std::unique_ptr<LayerImpl> layer_impl(
-        ReuseOrCreateLayerImpl(old_layers, layer, tree_impl));
-
-    tree_impl->AddToLayerList(layer_impl.get());
-    tree_impl->AddLayer(std::move(layer_impl));
+    if (!IsHidden(layer)) {
+      std::unique_ptr<LayerImpl> layer_impl(
+          ReuseOrCreateLayerImpl(old_layers, layer, tree_impl));
+
+      tree_impl->AddToLayerList(layer_impl.get());
+      tree_impl->AddLayer(std::move(layer_impl));
+    } else {
+      RemoveLayerShouldPushProperties(host, layer);
+    }
   }
   tree_impl->OnCanDrawStateChangedForTree();
 }