Refactor MutatorHostClient from LayerTreeHost to LayerTree.

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>
 
@@ skipping 28 matching lines @@
         &old_layer_map, source_tree->LayerById(id), tree_impl));
     tree_impl->AddLayer(std::move(layer_impl));
   }
 }
 
 void TreeSynchronizer::SynchronizeTrees(Layer* layer_root,
                                         LayerTreeImpl* tree_impl) {
   if (!layer_root) {
     tree_impl->DetachLayers();
   } else {
-    SynchronizeTreesInternal(layer_root->layer_tree_host(), tree_impl,
+    SynchronizeTreesInternal(layer_root->GetLayerTree(), tree_impl,
                              layer_root->layer_tree_host()->property_trees());
   }
 }
 
 void TreeSynchronizer::SynchronizeTrees(LayerTreeImpl* pending_tree,
                                         LayerTreeImpl* active_tree) {
   if (pending_tree->LayerListIsEmpty()) {
     active_tree->DetachLayers();
   } else {
     SynchronizeTreesInternal(pending_tree, active_tree,
@@ skipping 45 matching lines @@
                               active_tree);
 }
 
 void TreeSynchronizer::PushLayerProperties(LayerTree* host_tree,
                                            LayerTreeImpl* impl_tree) {
   PushLayerPropertiesInternal(host_tree->LayersThatShouldPushProperties(),
                               impl_tree);
 }
 
 }  // namespace cc