ChromeOS cryptohome should be able to use gaia id as user identifier.

chromeos/cryptohome/mock_homedir_methods.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 CHROMEOS_CRYPTOHOME_MOCK_HOMEDIR_METHODS_H_
 #define CHROMEOS_CRYPTOHOME_MOCK_HOMEDIR_METHODS_H_
 
 #include <string>
 
 #include "base/callback.h"
@@ skipping 33 matching lines @@
                void(const Identification& id,
                     const Authorization& auth,
                     const std::string& label,
                     const Callback& callback));
   MOCK_METHOD5(UpdateKeyEx,
                void(const Identification& id,
                     const Authorization& auth,
                     const KeyDefinition& key,
                     const std::string& signature,
                     const Callback& callback));
+  MOCK_METHOD3(RenameCryptohome,
+               void(const Identification& id_from,
+                    const Identification& id_to,
+                    const Callback& callback));
 
  private:
   bool success_;
   MountError return_code_;
 
   void DoCallback(const Callback& callback);
   void DoGetDataCallback(const GetKeyDataCallback& callback);
   void DoMountCallback(const MountCallback& callback);
 
   DISALLOW_COPY_AND_ASSIGN(MockHomedirMethods);
 };
 
 }  // namespace cryptohome
 
 #endif  // CHROMEOS_CRYPTOHOME_MOCK_HOMEDIR_METHODS_H_