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

chrome/browser/chromeos/login/easy_unlock/bootstrap_user_context_initializer.cc

 // 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.
 
 #include "chrome/browser/chromeos/login/easy_unlock/bootstrap_user_context_initializer.h"
 
 #include <vector>
 
 #include "base/strings/string_util.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chromeos/login/easy_unlock/easy_unlock_key_manager.h"
 #include "chrome/browser/chromeos/login/session/user_session_manager.h"
 #include "chrome/browser/chromeos/profiles/profile_helper.h"
 #include "chrome/browser/signin/easy_unlock_service_signin_chromeos.h"
+#include "chromeos/login/user_names.h"
+#include "components/user_manager/known_user.h"
 #include "components/user_manager/user_manager.h"
 #include "crypto/random.h"
 #include "google_apis/gaia/gaia_constants.h"
 #include "google_apis/gaia/gaia_urls.h"
 
 namespace chromeos {
 
 namespace {
 
 const int kMaxGaiaRetries = 5;
@@ skipping 143 matching lines @@
     scoped_ptr<base::DictionaryValue> user_info) {
   std::string email;
   std::string gaia_id;
   if (!user_info->GetString("email", &email) ||
       !user_info->GetString("id", &gaia_id)) {
     LOG(ERROR) << "Bad user info.";
     Notify(false);
     return;
   }
 
-  user_context_.SetUserID(email);
-  user_context_.SetGaiaID(gaia_id);
+  user_context_.SetAccountId(user_manager::known_user::GetAccountId(
+      login::CanonicalizeUserID(email), gaia_id));
   StartCheckExistingKeys();
 }
 
 void BootstrapUserContextInitializer::OnOAuthError() {
   LOG(ERROR) << "Auth error.";
   Notify(false);
 }
 
 void BootstrapUserContextInitializer::OnNetworkError(int response_code) {
   LOG(ERROR) << "Network error.";
@@ skipping 11 matching lines @@
       EasyUnlockService::Get(ProfileHelper::GetSigninProfile());
   service->RemoveObserver(this);
 
   service->AttemptAuth(
       user_context_.GetAccountId(),
       base::Bind(&BootstrapUserContextInitializer::OnEasyUnlockAuthenticated,
                  weak_ptr_factory_.GetWeakPtr()));
 }
 
 }  // namespace chromeos