ChromeOS: Fix DCHECK hit when logging under Guest

chrome/browser/chromeos/login/session/user_session_manager.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/session/user_session_manager.h"
 
 #include <stddef.h>
 
 #include <set>
 #include <string>
@@ skipping 1498 matching lines @@
   for (it = sessions.begin(); it != sessions.end(); ++it) {
     if (active_cryptohome_id == it->first)
       continue;
     pending_user_sessions_[(it->first).GetAccountId()] = it->second;
   }
   RestorePendingUserSessions();
 }
 
 void UserSessionManager::RestorePendingUserSessions() {
   if (pending_user_sessions_.empty()) {
-    user_manager::UserManager::Get()->SwitchToLastActiveUser();
+    // '>1' ignores "restart on signin" because of browser flags difference.
+    // In this case, last_session_active_account_id_ can carry account_id
+    // from the previous browser session.
+    if (user_manager::UserManager::Get()->GetLoggedInUsers().size() > 1)
+      user_manager::UserManager::Get()->SwitchToLastActiveUser();
+
     NotifyPendingUserSessionsRestoreFinished();
     return;
   }
 
   // Get next user to restore sessions and delete it from list.
   PendingUserSessions::const_iterator it = pending_user_sessions_.begin();
   const AccountId account_id = it->first;
   std::string user_id_hash = it->second;
   DCHECK(account_id.is_valid());
   DCHECK(!user_id_hash.empty());
@@ skipping 404 matching lines @@
           ->browser_policy_connector_chromeos()
           ->IsEnterpriseManaged()) {
     return false;
   }
 
   // Do not show end of life notification if this is a guest session
   return !profile->IsGuestSession();
 }
 
 }  // namespace chromeos