[Merge to M53] arc: Implement safe access to ArcAuthService.

components/user_manager/user_manager_base.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 "components/user_manager/user_manager_base.h"
 
 #include <stddef.h>
 #include <set>
 #include <utility>
 
@@ skipping 625 matching lines @@
   // Data belonging to the guest and demo users is always ephemeral.
   if (IsGuestAccountId(account_id) || IsDemoApp(account_id))
     return true;
 
   // Data belonging to the public accounts is always ephemeral.
   const User* user = FindUser(account_id);
   if (user && user->GetType() == USER_TYPE_PUBLIC_ACCOUNT)
     return true;
 
   // Ephemeral users.
-  if (user && user->GetType() == USER_TYPE_REGULAR &&
+  if (AreEphemeralUsersEnabled() && user &&
+      user->GetType() == USER_TYPE_REGULAR &&
       FindUserInList(account_id) == nullptr) {
     return true;
   }
 
   return false;
 }
 
 void UserManagerBase::AddObserver(UserManager::Observer* obs) {
   DCHECK(task_runner_->RunsTasksOnCurrentThread());
   observer_list_.AddObserver(obs);
@@ skipping 416 matching lines @@
 }
 
 void UserManagerBase::DeleteUser(User* user) {
   const bool is_active_user = (user == active_user_);
   delete user;
   if (is_active_user)
     active_user_ = nullptr;
 }
 
 }  // namespace user_manager