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

chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc

 // Copyright 2013 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/ui/webui/chromeos/login/gaia_screen_handler.h"
 
 #include "ash/system/chromeos/devicetype_utils.h"
 #include "base/bind.h"
 #include "base/guid.h"
 #include "base/logging.h"
@@ skipping 423 matching lines @@
     const std::string& gaps_cookie) {
   if (!Delegate())
     return;
 
   DCHECK(!email.empty());
   DCHECK(!gaia_id.empty());
   const std::string sanitized_email = gaia::SanitizeEmail(email);
   Delegate()->SetDisplayEmail(sanitized_email);
 
   UserContext user_context(GetAccountId(email, gaia_id));
-  user_context.SetGaiaID(gaia_id);
   user_context.SetKey(Key(password));
   user_context.SetAuthCode(auth_code);
   user_context.SetAuthFlow(using_saml
                                ? UserContext::AUTH_FLOW_GAIA_WITH_SAML
                                : UserContext::AUTH_FLOW_GAIA_WITHOUT_SAML);
   user_context.SetGAPSCookie(gaps_cookie);
   Delegate()->CompleteLogin(user_context);
 }
 
 void GaiaScreenHandler::HandleCompleteAuthenticationAuthCodeOnly(
@@ skipping 63 matching lines @@
     return;
 
   if (using_saml && !using_saml_api_)
     RecordSAMLScrapingVerificationResultInHistogram(true);
 
   DCHECK(!typed_email.empty());
   DCHECK(!gaia_id.empty());
   const std::string sanitized_email = gaia::SanitizeEmail(typed_email);
   Delegate()->SetDisplayEmail(sanitized_email);
   UserContext user_context(GetAccountId(typed_email, gaia_id));
-  user_context.SetGaiaID(gaia_id);
   user_context.SetKey(Key(password));
   user_context.SetAuthFlow(using_saml
                                ? UserContext::AUTH_FLOW_GAIA_WITH_SAML
                                : UserContext::AUTH_FLOW_GAIA_WITHOUT_SAML);
   Delegate()->CompleteLogin(user_context);
 
   if (test_expects_complete_login_) {
     VLOG(2) << "Complete test login for " << typed_email
             << ", requested=" << test_user_;
 
@@ skipping 253 matching lines @@
 bool GaiaScreenHandler::IsRestrictiveProxy() const {
   return !disable_restrictive_proxy_check_for_test_ &&
          !IsOnline(captive_portal_status_);
 }
 
 void GaiaScreenHandler::DisableRestrictiveProxyCheckForTest() {
   disable_restrictive_proxy_check_for_test_ = true;
 }
 
 }  // namespace chromeos