chrome: Cleanup class/struct forward declarations

chrome/browser/chromeos/login/ui/login_display_host_impl.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_UI_LOGIN_DISPLAY_HOST_IMPL_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_UI_LOGIN_DISPLAY_HOST_IMPL_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 16 matching lines @@
 #include "chromeos/dbus/session_manager_client.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "ui/display/display_observer.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/keyboard/keyboard_controller_observer.h"
 #include "ui/views/widget/widget_removals_observer.h"
 #include "ui/wm/public/scoped_drag_drop_disabler.h"
 
-class PrefService;
 class ScopedKeepAlive;
 
-namespace content {
-class RenderFrameHost;
-class WebContents;
-}
-
 namespace chromeos {
 
 class DemoAppLauncher;
 class FocusRingController;
 class KeyboardDrivenOobeKeyHandler;
 class WebUILoginDisplay;
 class WebUILoginView;
 
 // An implementation class for OOBE/login WebUI screen host.
 // It encapsulates controllers, wallpaper integration and flow.
@@ skipping 264 matching lines @@
 
   base::WeakPtrFactory<LoginDisplayHostImpl> pointer_factory_;
   base::WeakPtrFactory<LoginDisplayHostImpl> animation_weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(LoginDisplayHostImpl);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_UI_LOGIN_DISPLAY_HOST_IMPL_H_