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

chrome/browser/chromeos/login/session/chrome_session_manager.cc

Index: chrome/browser/chromeos/login/session/chrome_session_manager.cc
diff --git a/chrome/browser/chromeos/login/session/chrome_session_manager.cc b/chrome/browser/chromeos/login/session/chrome_session_manager.cc
index 1802d82e533a5dd4f4164ff25de070d90cb95ac9..7c354a0d346a09644b2ea22ba8a059eeaff9fe9d 100644
--- a/chrome/browser/chromeos/login/session/chrome_session_manager.cc
+++ b/chrome/browser/chromeos/login/session/chrome_session_manager.cc
@@ -16,6 +16,8 @@
 #include "chrome/browser/chromeos/login/session/stub_login_session_manager_delegate.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chromeos/chromeos_switches.h"
+#include "chromeos/cryptohome/cryptohome_parameters.h"
+#include "chromeos/login/auth/utils.h"
 #include "chromeos/login/user_names.h"
 #include "components/signin/core/account_id/account_id.h"
 
@@ -45,8 +47,10 @@ ChromeSessionManager::CreateSessionManager(
   bool force_login_screen_in_test =
       parsed_command_line.HasSwitch(switches::kForceLoginManagerInTests);
 
-  const AccountId login_account_id(AccountId::FromUserEmail(
-      parsed_command_line.GetSwitchValueASCII(switches::kLoginUser)));
+  const std::string cryptohome_id =
+      parsed_command_line.GetSwitchValueASCII(switches::kLoginUser);
+  const AccountId login_account_id(cryptohome::GetAccountId(
+      cryptohome::Identification::FromString(cryptohome_id)));
 
   KioskAppManager::RemoveObsoleteCryptohomes();