[exp] cc: Introduce cc::CompositorMutator.

cc/test/fake_layer_tree_host.cc

 // Copyright 2013 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/test/fake_layer_tree_host.h"
 
 namespace cc {
 FakeLayerTreeHost::FakeLayerTreeHost(FakeLayerTreeHostClient* client,
                                      const LayerTreeSettings& settings)
-    : LayerTreeHost(client, NULL, NULL, settings),
+    : LayerTreeHost(client, NULL, NULL, NULL, settings),
       client_(client),
       host_impl_(settings, &proxy_, &manager_),
       needs_commit_(false) {
   client_->SetLayerTreeHost(this);
 }
 
 scoped_ptr<FakeLayerTreeHost> FakeLayerTreeHost::Create(
     FakeLayerTreeHostClient* client) {
   LayerTreeSettings settings;
   settings.verify_property_trees = true;
@@ skipping 17 matching lines @@
 
   scoped_ptr<LayerImpl> layer_impl = TreeSynchronizer::SynchronizeTrees(
       root_layer(), old_root_layer_impl.Pass(), active_tree());
   TreeSynchronizer::PushProperties(root_layer(), layer_impl.get());
 
   active_tree()->SetRootLayer(layer_impl.Pass());
   return active_tree()->root_layer();
 }
 
 }  // namespace cc