Make UserActivityDetector a singleton

chrome/browser/chromeos/kiosk_mode/kiosk_mode_idle_logout_unittest.cc

 // Copyright (c) 2012 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/kiosk_mode/kiosk_mode_idle_logout.h"
 
-#include "ash/shell.h"
 #include "ash/test/ash_test_base.h"
 #include "base/bind.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/synchronization/waitable_event.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/chromeos/settings/device_settings_test_helper.h"
 #include "components/user_manager/user_manager.h"
 #include "content/public/browser/notification_registrar.h"
 #include "content/public/browser/notification_service.h"
@@ skipping 19 matching lines @@
   }
 
   bool LoginUserObserverRegistered() {
     return idle_logout_->registrar_.IsRegistered(
         idle_logout_,
         chrome::NOTIFICATION_LOGIN_USER_CHANGED,
         content::NotificationService::AllSources());
   }
 
   bool UserActivityObserverRegistered() {
-    return ash::Shell::GetInstance()->user_activity_detector()->HasObserver(
-        idle_logout_);
+    return wm::UserActivityDetector::Get()->HasObserver(idle_logout_);
   }
 
   ScopedDeviceSettingsTestHelper device_settings_test_helper_;
 
   KioskModeIdleLogout* idle_logout_;
   content::NotificationRegistrar registrar_;
 };
 
 // http://crbug.com/177918
 TEST_F(KioskModeIdleLogoutTest, DISABLED_CheckObserversBeforeUserLogin) {
@@ skipping 11 matching lines @@
       // checking for the current logged in user in our observer anyway, giving
       // NoDetails here is fine.
       content::NotificationService::NoDetails());
 
   RunAllPendingInMessageLoop();
   EXPECT_FALSE(LoginUserObserverRegistered());
   EXPECT_TRUE(UserActivityObserverRegistered());
 }
 
 }  // namespace chromeos