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

chrome/browser/chromeos/policy/affiliation_test_helper.cc

 // Copyright 2015 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 "chrome/browser/chromeos/policy/affiliation_test_helper.h"
 
 #include <stdint.h>
 
 #include <string>
 #include <vector>
 
@@ skipping 87 matching lines @@
   ListPrefUpdate users_pref(g_browser_process->local_state(), "LoggedInUsers");
   users_pref->AppendIfNotPresent(new base::StringValue(user_id));
   chromeos::StartupUtils::MarkOobeCompleted();
 }
 
 void LoginUser(const std::string& user_id) {
   chromeos::test::UserSessionManagerTestApi session_manager_test_api(
       chromeos::UserSessionManager::GetInstance());
   session_manager_test_api.SetShouldObtainTokenHandleInTests(false);
 
-  chromeos::UserContext user_context(AccountId::FromUserEmail(user_id));
-  user_context.SetGaiaID("gaia-id-" + user_id);
+  chromeos::UserContext user_context(
+      AccountId::FromUserEmailGaiaId(user_id, "gaia-id-" + user_id));
   user_context.SetKey(chromeos::Key("password"));
   if (user_id == kEnterpriseUser) {
     user_context.SetRefreshToken(kFakeRefreshToken);
   }
   chromeos::ExistingUserController* controller =
       chromeos::ExistingUserController::current_controller();
   CHECK(controller);
   content::WindowedNotificationObserver observer(
       chrome::NOTIFICATION_SESSION_STARTED,
       content::NotificationService::AllSources());
@@ skipping 11 matching lines @@
 }
 
 void AppendCommandLineSwitchesForLoginManager(base::CommandLine* command_line) {
   command_line->AppendSwitch(chromeos::switches::kLoginManager);
   command_line->AppendSwitch(chromeos::switches::kForceLoginManagerInTests);
 }
 
 }  // namespace affiliation_test_helper
 
 }  // namespace policy