chrome: Cleanup class/struct forward declarations

chrome/browser/chromeos/login/lock/webui_screen_locker.h

 // 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.
 
 #ifndef CHROME_BROWSER_CHROMEOS_LOGIN_LOCK_WEBUI_SCREEN_LOCKER_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_LOCK_WEBUI_SCREEN_LOCKER_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 15 matching lines @@
 #include "ui/keyboard/keyboard_controller_observer.h"
 #include "ui/views/widget/widget.h"
 #include "ui/views/widget/widget_observer.h"
 
 namespace content {
 class WebUI;
 }
 
 namespace chromeos {
 
-class OobeUI;
 class ScreenLocker;
 class WebUILoginDisplay;
 
 namespace login {
 class NetworkStateHelper;
 }
 
 namespace test {
 class WebUIScreenLockerTester;
 }
@@ skipping 135 matching lines @@
   bool is_observing_keyboard_ = false;
 
   base::WeakPtrFactory<WebUIScreenLocker> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WebUIScreenLocker);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_LOCK_WEBUI_SCREEN_LOCKER_H_