Add support for (de)serializing LayerTreeHost.

cc/trees/layer_tree_host.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/layer_tree_host.h"
 
 #include <algorithm>
 #include <stack>
 #include <string>
 
@@ skipping 17 matching lines @@
 #include "cc/debug/frame_viewer_instrumentation.h"
 #include "cc/debug/rendering_stats_instrumentation.h"
 #include "cc/input/layer_selection_bound.h"
 #include "cc/input/page_scale_animation.h"
 #include "cc/layers/heads_up_display_layer.h"
 #include "cc/layers/heads_up_display_layer_impl.h"
 #include "cc/layers/layer.h"
 #include "cc/layers/layer_iterator.h"
 #include "cc/layers/layer_settings.h"
 #include "cc/layers/painted_scrollbar_layer.h"
+#include "cc/proto/layer_tree_host.pb.h"
 #include "cc/resources/ui_resource_request.h"
 #include "cc/scheduler/begin_frame_source.h"
 #include "cc/trees/draw_property_utils.h"
 #include "cc/trees/layer_tree_host_client.h"
 #include "cc/trees/layer_tree_host_common.h"
 #include "cc/trees/layer_tree_host_impl.h"
 #include "cc/trees/layer_tree_impl.h"
 #include "cc/trees/proxy_main.h"
 #include "cc/trees/single_thread_proxy.h"
 #include "cc/trees/tree_synchronizer.h"
@@ skipping 1214 matching lines @@
          !task_runner_provider_->HasImplThread());
   return compositor_mode_ == CompositorMode::SingleThreaded;
 }
 
 bool LayerTreeHost::IsThreaded() const {
   DCHECK(compositor_mode_ != CompositorMode::Threaded ||
          task_runner_provider_->HasImplThread());
   return compositor_mode_ == CompositorMode::Threaded;
 }
 
+void LayerTreeHost::ToProtobufForCommit(proto::LayerTreeHost* proto) const {}
+
+void LayerTreeHost::FromProtobufForCommit(const proto::LayerTreeHost& proto) {}
+
 }  // namespace cc