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

chrome/browser/chromeos/login/demo_mode/demo_app_launcher.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/demo_mode/demo_app_launcher.h"
 
 #include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "chrome/browser/chromeos/app_mode/kiosk_app_manager.h"
@@ skipping 31 matching lines @@
     demo_app_path_ = new base::FilePath(kDefaultDemoAppPath);
 }
 
 DemoAppLauncher::~DemoAppLauncher() {
   delete demo_app_path_;
 }
 
 void DemoAppLauncher::StartDemoAppLaunch() {
   DVLOG(1) << "Launching demo app...";
   // user_id = DemoAppUserId, force_emphemeral = true, delegate = this.
-  kiosk_profile_loader_.reset(new KioskProfileLoader(
-      login::DemoAccountId().GetUserEmail(), true, this));
+  kiosk_profile_loader_.reset(
+      new KioskProfileLoader(login::DemoAccountId(), true, this));
   kiosk_profile_loader_->Start();
 }
 
 // static
-bool DemoAppLauncher::IsDemoAppSession(const std::string& user_id) {
-  return user_id == login::DemoAccountId().GetUserEmail();
+bool DemoAppLauncher::IsDemoAppSession(const AccountId& account_id) {
+  return account_id == login::DemoAccountId();
 }
 
 // static
 void DemoAppLauncher::SetDemoAppPathForTesting(const base::FilePath& path) {
   delete demo_app_path_;
   demo_app_path_ = new base::FilePath(path);
 }
 
 void DemoAppLauncher::OnProfileLoaded(Profile* profile) {
   DVLOG(1) << "Profile loaded... Starting demo app launch.";
@@ skipping 33 matching lines @@
 
   LoginDisplayHost::default_host()->Finalize();
 }
 
 void DemoAppLauncher::OnProfileLoadFailed(KioskAppLaunchError::Error error) {
   LOG(ERROR) << "Loading the Kiosk Profile failed: " <<
       KioskAppLaunchError::GetErrorMessage(error);
 }
 
 }  // namespace chromeos