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

chrome/browser/extensions/extension_browsertest.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 "chrome/browser/extensions/extension_browsertest.h"
 
 #include <stddef.h>
 #include <utility>
 #include <vector>
 
@@ skipping 120 matching lines @@
   // We don't want any warning bubbles for, e.g., unpacked extensions.
   ExtensionMessageBubbleFactory::set_override_for_tests(
       ExtensionMessageBubbleFactory::OVERRIDE_DISABLED);
 
 #if defined(OS_CHROMEOS)
   if (set_chromeos_user_) {
     // This makes sure that we create the Default profile first, with no
     // ExtensionService and then the real profile with one, as we do when
     // running on chromeos.
     command_line->AppendSwitchASCII(chromeos::switches::kLoginUser,
-                                    "TestUser@gmail.com");
+                                    "testuser@gmail.com");
     command_line->AppendSwitchASCII(chromeos::switches::kLoginProfile, "user");
   }
 #endif
 }
 
 void ExtensionBrowserTest::SetUpOnMainThread() {
   InProcessBrowserTest::SetUpOnMainThread();
   observer_.reset(new ExtensionTestNotificationObserver(browser()));
   if (extension_service()->updater()) {
     extension_service()->updater()->SetExtensionCacheForTesting(
@@ skipping 502 matching lines @@
   return extensions::browsertest_util::ExecuteScriptInBackgroundPage(
       profile(), extension_id, script);
 }
 
 bool ExtensionBrowserTest::ExecuteScriptInBackgroundPageNoWait(
     const std::string& extension_id,
     const std::string& script) {
   return extensions::browsertest_util::ExecuteScriptInBackgroundPageNoWait(
       profile(), extension_id, script);
 }