Activate LayerImpl tree with sync+push instead of pointer swap

cc/layer_tree_impl.cc

Index: cc/layer_tree_impl.cc
diff --git a/cc/layer_tree_impl.cc b/cc/layer_tree_impl.cc
index 328116a7c64ac5d7d7346098b98228890b234cb3..a2e2b3f7437c8d0400c27d402eb35b4f228951d0 100644
--- a/cc/layer_tree_impl.cc
+++ b/cc/layer_tree_impl.cc
@@ -234,6 +234,10 @@ void LayerTreeImpl::ResetContentsTexturesPurged() {
   layer_tree_host_impl_->OnCanDrawStateChangedForTree(this);
 }
 
+Proxy* LayerTreeImpl::proxy() const {
+  return layer_tree_host_impl_->proxy();
+}
+
 const LayerTreeSettings& LayerTreeImpl::settings() const {
   return layer_tree_host_impl_->settings();
 }
@@ -266,6 +270,10 @@ bool LayerTreeImpl::IsPendingTree() const {
   return layer_tree_host_impl_->pendingTree() == this;
 }
 
+bool LayerTreeImpl::IsRecycleTree() const {
+  return layer_tree_host_impl_->recycleTree() == this;
+}
+
 LayerImpl* LayerTreeImpl::FindActiveTreeLayerById(int id) {
   LayerTreeImpl* tree = layer_tree_host_impl_->activeTree();
   if (!tree)