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

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

Index: chrome/browser/chromeos/login/session/user_session_manager.cc
diff --git a/chrome/browser/chromeos/login/session/user_session_manager.cc b/chrome/browser/chromeos/login/session/user_session_manager.cc
index 3eda1fd935944b3bcde79644575b06dfb3538368..c0cd6d2a83aa6e26ef17392949cd82bc87b6bbfc 100644
--- a/chrome/browser/chromeos/login/session/user_session_manager.cc
+++ b/chrome/browser/chromeos/login/session/user_session_manager.cc
@@ -86,6 +86,7 @@
 #include "chromeos/dbus/dbus_thread_manager.h"
 #include "chromeos/dbus/session_manager_client.h"
 #include "chromeos/login/auth/stub_authenticator.h"
+#include "chromeos/login/auth/utils.h"
 #include "chromeos/login/user_names.h"
 #include "chromeos/network/portal_detector/network_portal_detector.h"
 #include "chromeos/network/portal_detector/network_portal_detector_strategy.h"
@@ -894,7 +895,7 @@ void UserSessionManager::StartCrosSession() {
   BootTimesRecorder* btl = BootTimesRecorder::Get();
   btl->AddLoginTimeMarker("StartSession-Start", false);
   DBusThreadManager::Get()->GetSessionManagerClient()->StartSession(
-      user_context_.GetAccountId().GetUserEmail());
+      cryptohome::Identification(user_context_.GetAccountId()).id());
   btl->AddLoginTimeMarker("StartSession-End", false);
 }
 
@@ -1426,13 +1427,16 @@ void UserSessionManager::OnRestoreActiveSessions(
   user_manager::UserManager* user_manager = user_manager::UserManager::Get();
   DCHECK_EQ(1u, user_manager->GetLoggedInUsers().size());
   DCHECK(user_manager->GetActiveUser());
-  std::string active_user_id = user_manager->GetActiveUser()->email();
+  const std::string active_cryptohome_id =
+      cryptohome::Identification(user_manager->GetActiveUser()->GetAccountId())
+          .id();
 
   SessionManagerClient::ActiveSessionsMap::const_iterator it;
   for (it = sessions.begin(); it != sessions.end(); ++it) {
-    if (active_user_id == it->first)
+    if (active_cryptohome_id == it->first)
       continue;
-    pending_user_sessions_[it->first] = it->second;
+    pending_user_sessions_[cryptohome::GetAccountId(
+        cryptohome::Identification::FromString(it->first))] = it->second;
   }
   RestorePendingUserSessions();
 }
@@ -1445,13 +1449,12 @@ void UserSessionManager::RestorePendingUserSessions() {
   }
 
   // Get next user to restore sessions and delete it from list.
-  SessionManagerClient::ActiveSessionsMap::const_iterator it =
-      pending_user_sessions_.begin();
-  std::string user_id = it->first;
+  PendingUserSessions::const_iterator it = pending_user_sessions_.begin();
+  const AccountId account_id = it->first;
   std::string user_id_hash = it->second;
-  DCHECK(!user_id.empty());
+  DCHECK(account_id.is_valid());
   DCHECK(!user_id_hash.empty());
-  pending_user_sessions_.erase(user_id);
+  pending_user_sessions_.erase(account_id);
 
   // Check that this user is not logged in yet.
   user_manager::UserList logged_in_users =
@@ -1461,7 +1464,7 @@ void UserSessionManager::RestorePendingUserSessions() {
        it != logged_in_users.end();
        ++it) {
     const user_manager::User* user = (*it);
-    if (user->email() == user_id) {
+    if (user->GetAccountId() == account_id) {
       user_already_logged_in = true;
       break;
     }
@@ -1469,7 +1472,7 @@ void UserSessionManager::RestorePendingUserSessions() {
   DCHECK(!user_already_logged_in);
 
   if (!user_already_logged_in) {
-    UserContext user_context(AccountId::FromUserEmail(user_id));
+    UserContext user_context(account_id);
     user_context.SetUserIDHash(user_id_hash);
     user_context.SetIsUsingOAuth(false);