Setup LayerTree class, refactor 2 functions from LayerTreeHost to it.

cc/trees/tree_synchronizer.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/trees/tree_synchronizer.h"
 
 #include <stddef.h>
 
 #include <set>
 
 #include "base/logging.h"
 #include "base/trace_event/trace_event.h"
 #include "cc/layers/layer.h"
 #include "cc/layers/layer_collections.h"
 #include "cc/layers/layer_impl.h"
+#include "cc/trees/layer_tree.h"
 #include "cc/trees/layer_tree_host.h"
 #include "cc/trees/layer_tree_impl.h"
 
 namespace cc {
 
 template <typename LayerTreeType>
 void SynchronizeTreesInternal(LayerTreeType* source_tree,
                               LayerTreeImpl* tree_impl,
                               PropertyTrees* property_trees) {
   DCHECK(tree_impl);
@@ skipping 71 matching lines @@
     layer->PushPropertiesTo(layer_impl);
   }
 }
 
 void TreeSynchronizer::PushLayerProperties(LayerTreeImpl* pending_tree,
                                            LayerTreeImpl* active_tree) {
   PushLayerPropertiesInternal(pending_tree->LayersThatShouldPushProperties(),
                               active_tree);
 }
 
-void TreeSynchronizer::PushLayerProperties(LayerTreeHost* host_tree,
+void TreeSynchronizer::PushLayerProperties(LayerTree* host_tree,
                                            LayerTreeImpl* impl_tree) {
   PushLayerPropertiesInternal(host_tree->LayersThatShouldPushProperties(),
                               impl_tree);
 }
 
+void TreeSynchronizer::PushLayerProperties(LayerTreeHost* host_tree,
+                                           LayerTreeImpl* impl_tree) {
+  PushLayerProperties(host_tree->GetLayerTree(), impl_tree);
+}
+
 }  // namespace cc