[ABANDONED] Make it possible to send unique_ptr<Value> over IPC/Mojo.

mojo/common/common_custom_types.mojom

 // 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.
 
 module mojo.common.mojom;
 
 [Native]
 struct FilePath;
 
 [Native]
@@ skipping 18 matching lines @@
 struct String16 {
   array<uint16> data;
 };
 
 // Corresponds to |base::UnguessableToken| in base/unguessable_token.h
 struct UnguessableToken {
   uint64 high;
   uint64 low;
 };
 
+[Native]
+struct Value;
+
 // Corresponds to |base::Version| in base/version.h
 struct Version {
   array<uint32> components;
 };