Add SurfaceReference class.

cc/surfaces/local_frame_id.h

 // Copyright 2016 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_LOCAL_FRAME_ID_H_
 #define CC_SURFACES_LOCAL_FRAME_ID_H_
 
 #include <inttypes.h>
 
 #include <iosfwd>
 #include <string>
 #include <tuple>
 
 #include "base/hash.h"
 #include "base/unguessable_token.h"
+#include "mojo/public/cpp/bindings/struct_traits.h"
 
 namespace cc {
+namespace mojom {
+class LocalFrameIdDataView;
+}
 
 class LocalFrameId {
  public:
   constexpr LocalFrameId() : local_id_(0) {}
 
   constexpr LocalFrameId(const LocalFrameId& other)
       : local_id_(other.local_id_), nonce_(other.nonce_) {}
 
   constexpr LocalFrameId(uint32_t local_id, const base::UnguessableToken& nonce)
       : local_id_(local_id), nonce_(nonce) {}
@@ skipping 18 matching lines @@
   }
 
   size_t hash() const {
     return base::HashInts(
         local_id_, static_cast<uint64_t>(base::UnguessableTokenHash()(nonce_)));
   }
 
   std::string ToString() const;
 
  private:
+  friend struct mojo::StructTraits<mojom::LocalFrameIdDataView, LocalFrameId>;
+
   uint32_t local_id_;
   base::UnguessableToken nonce_;
 };
 
 std::ostream& operator<<(std::ostream& out, const LocalFrameId& local_frame_id);
 
 struct LocalFrameIdHash {
   size_t operator()(const LocalFrameId& key) const { return key.hash(); }
 };
 
 }  // namespace cc
 
 #endif  // CC_SURFACES_LOCAL_FRAME_ID_H_