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

chromeos/attestation/mock_attestation_flow.cc

 // Copyright (c) 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.
 
 #include "chromeos/attestation/mock_attestation_flow.h"
 
 #include "base/memory/scoped_ptr.h"
+#include "components/signin/core/account_id/account_id.h"
 
 using testing::_;
 using testing::DefaultValue;
 using testing::Invoke;
 
 namespace chromeos {
 namespace attestation {
 
 FakeServerProxy::FakeServerProxy() : result_(true) {}
 
@@ skipping 27 matching lines @@
 
 MockObserver::~MockObserver() {}
 
 MockAttestationFlow::MockAttestationFlow()
     : AttestationFlow(NULL, NULL, scoped_ptr<ServerProxy>()) {}
 
 MockAttestationFlow::~MockAttestationFlow() {}
 
 }  // namespace attestation
 }  // namespace chromeos