Add SurfaceReference class.

cc/surfaces/surface_id.h

 // Copyright 2014 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_SURFACES_SURFACE_ID_H_
 #define CC_SURFACES_SURFACE_ID_H_
 
 #include <stdint.h>
 
 #include <iosfwd>
 #include <string>
 
 #include "base/format_macros.h"
 #include "base/hash.h"
 #include "cc/surfaces/frame_sink_id.h"
 #include "cc/surfaces/local_frame_id.h"
+#include "mojo/public/cpp/bindings/struct_traits.h"
 
 namespace cc {
+namespace mojom {
+class SurfaceIdDataView;
+}
 
 class SurfaceId {
  public:
   constexpr SurfaceId() = default;
 
   constexpr SurfaceId(const SurfaceId& other) = default;
 
   // A SurfaceId consists of two components: FrameSinkId and LocalFrameId.
   // A |frame_sink_id| consists of two components; one is allocated by the
   // display compositor service and one is allocated by the client. The
@@ skipping 26 matching lines @@
   }
 
   bool operator!=(const SurfaceId& other) const { return !(*this == other); }
 
   bool operator<(const SurfaceId& other) const {
     return std::tie(frame_sink_id_, local_frame_id_) <
            std::tie(other.frame_sink_id_, other.local_frame_id_);
   }
 
  private:
+  friend struct mojo::StructTraits<mojom::SurfaceIdDataView, SurfaceId>;
+
   // See SurfaceIdAllocator::GenerateId.
   FrameSinkId frame_sink_id_;
   LocalFrameId local_frame_id_;
 };
 
 std::ostream& operator<<(std::ostream& out, const SurfaceId& surface_id);
 
 struct SurfaceIdHash {
   size_t operator()(const SurfaceId& key) const { return key.hash(); }
 };
 
 }  // namespace cc
 
 #endif  // CC_SURFACES_SURFACE_ID_H_