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

chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager_policy_browsertest.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 <stdint.h>
 
 #include <string>
 #include <vector>
 
 #include "ash/desktop_background/desktop_background_controller.h"
@@ skipping 132 matching lines @@
         AccountId::FromUserEmail(LoginManagerTest::kEnterpriseUser2));
   }
 
   scoped_ptr<policy::UserPolicyBuilder> GetUserPolicyBuilder(
       const AccountId& account_id) {
     scoped_ptr<policy::UserPolicyBuilder>
         user_policy_builder(new policy::UserPolicyBuilder());
     base::FilePath user_keys_dir;
     EXPECT_TRUE(PathService::Get(DIR_USER_POLICY_KEYS, &user_keys_dir));
     const std::string sanitized_user_id =
-        CryptohomeClient::GetStubSanitizedUsername(account_id.GetUserEmail());
+        CryptohomeClient::GetStubSanitizedUsername(
+            cryptohome::Identification(account_id));
     const base::FilePath user_key_file =
         user_keys_dir.AppendASCII(sanitized_user_id)
                      .AppendASCII("policy.pub");
     std::vector<uint8_t> user_key_bits;
     EXPECT_TRUE(user_policy_builder->GetSigningKey()->
                 ExportPublicKey(&user_key_bits));
     EXPECT_TRUE(base::CreateDirectory(user_key_file.DirName()));
     EXPECT_EQ(base::WriteFile(
                   user_key_file,
                   reinterpret_cast<const char*>(user_key_bits.data()),
@@ skipping 81 matching lines @@
     const AccountId& account_id = testUsers_[user_number];
     policy::UserPolicyBuilder* builder =
         user_policy_builders_[user_number].get();
     if (!filename.empty()) {
       builder->payload().
           mutable_wallpaperimage()->set_value(ConstructPolicy(filename));
     } else {
       builder->payload().Clear();
     }
     builder->Build();
-    fake_session_manager_client_->set_user_policy(account_id.GetUserEmail(),
-                                                  builder->GetBlob());
+    fake_session_manager_client_->set_user_policy(
+        cryptohome::Identification(account_id), builder->GetBlob());
     const user_manager::User* user =
         user_manager::UserManager::Get()->FindUser(account_id);
     ASSERT_TRUE(user);
     policy::CloudPolicyStore* store = GetStoreForUser(user);
     ASSERT_TRUE(store);
     store->Load();
     ASSERT_EQ(policy::CloudPolicyStore::STATUS_OK, store->status());
     ASSERT_EQ(policy::CloudPolicyValidatorBase::VALIDATION_OK,
               store->validation_status());
   }
@@ skipping 140 matching lines @@
 
 IN_PROC_BROWSER_TEST_F(WallpaperManagerPolicyTest, PersistOverLogout) {
   LoginUser(testUsers_[0].GetUserEmail());
 
   // Wait until wallpaper has been loaded.
   RunUntilWallpaperChangeCount(1);
   ASSERT_EQ(kRedImageColor, GetAverageBackgroundColor());
 }
 
 }  // namespace chromeos