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

chrome/browser/chromeos/app_mode/kiosk_profile_loader.cc

Index: chrome/browser/chromeos/app_mode/kiosk_profile_loader.cc
diff --git a/chrome/browser/chromeos/app_mode/kiosk_profile_loader.cc b/chrome/browser/chromeos/app_mode/kiosk_profile_loader.cc
index d856520465ebd430e40e4e5f3558446e0df33a65..4c2fe6140a2582198c5b8b048eaf820068ea27dd 100644
--- a/chrome/browser/chromeos/app_mode/kiosk_profile_loader.cc
+++ b/chrome/browser/chromeos/app_mode/kiosk_profile_loader.cc
@@ -119,10 +119,10 @@ class KioskProfileLoader::CryptohomedChecker
 ////////////////////////////////////////////////////////////////////////////////
 // KioskProfileLoader
 
-KioskProfileLoader::KioskProfileLoader(const std::string& app_user_id,
+KioskProfileLoader::KioskProfileLoader(const AccountId& app_account_id,
                                        bool use_guest_mount,
                                        Delegate* delegate)
-    : user_id_(app_user_id),
+    : account_id_(app_account_id),
       use_guest_mount_(use_guest_mount),
       delegate_(delegate) {}
 
@@ -137,7 +137,7 @@ void KioskProfileLoader::Start() {
 
 void KioskProfileLoader::LoginAsKioskAccount() {
   login_performer_.reset(new ChromeLoginPerformer(this));
-  login_performer_->LoginAsKioskAccount(user_id_, use_guest_mount_);
+  login_performer_->LoginAsKioskAccount(account_id_, use_guest_mount_);
 }
 
 void KioskProfileLoader::ReportLaunchResult(KioskAppLaunchError::Error error) {
@@ -160,7 +160,7 @@ void KioskProfileLoader::OnAuthSuccess(const UserContext& user_context) {
   // user as a demo user.
   UserContext context = user_context;
   if (context.GetAccountId() == login::GuestAccountId())
-    context.SetUserID(login::DemoAccountId().GetUserEmail());
+    context.SetAccountId(login::DemoAccountId());
   UserSessionManager::GetInstance()->StartSession(
       context, UserSessionManager::PRIMARY_USER_SESSION,
       false,  // has_auth_cookies