Add support for (de)serializing HeadsUpDisplayLayer

cc/layers/heads_up_display_layer.h

 // Copyright 2012 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.
 
 #ifndef CC_LAYERS_HEADS_UP_DISPLAY_LAYER_H_
 #define CC_LAYERS_HEADS_UP_DISPLAY_LAYER_H_
 
 #include <string>
 
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "cc/base/cc_export.h"
 #include "cc/layers/layer.h"
 
 namespace cc {
 
+namespace proto {
+class LayerNode;
+}  // namespace proto
+
 class CC_EXPORT HeadsUpDisplayLayer : public Layer {
  public:
   static scoped_refptr<HeadsUpDisplayLayer> Create(
       const LayerSettings& settings);
 
   void PrepareForCalculateDrawProperties(
       const gfx::Size& device_viewport, float device_scale_factor);
 
   scoped_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl) override;
 
+  void SetTypeForProtoSerialization(proto::LayerNode* proto) const override;
+
  protected:
   explicit HeadsUpDisplayLayer(const LayerSettings& settings);
   bool HasDrawableContent() const override;
 
  private:
   ~HeadsUpDisplayLayer() override;
 
   DISALLOW_COPY_AND_ASSIGN(HeadsUpDisplayLayer);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_HEADS_UP_DISPLAY_LAYER_H_