chrome: Cleanup class/struct forward declarations

chrome/browser/chromeos/ui/idle_app_name_notification_view.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_UI_IDLE_APP_NAME_NOTIFICATION_VIEW_H_
 #define CHROME_BROWSER_CHROMEOS_UI_IDLE_APP_NAME_NOTIFICATION_VIEW_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "base/strings/string16.h"
 
 namespace extensions {
 class Extension;
 }  // namespace extensions
 
-namespace views {
-class Widget;
-}  // namespace views
-
 namespace chromeos {
 
 class IdleAppNameNotificationDelegateView;
 
 // A class which creates a message which shows the currently running applicaion
 // name and its creator.
 class IdleAppNameNotificationView {
  public:
   // |message_visibility_time_in_ms| is the time the message is fully visible.
   // |animation_time_ms| is the transition time for the message to show or hide.
@@ skipping 20 matching lines @@
 
   // A reference to an existing message.
   IdleAppNameNotificationDelegateView* view_;
 
   DISALLOW_COPY_AND_ASSIGN(IdleAppNameNotificationView);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_UI_IDLE_APP_NAME_NOTIFICATION_VIEW_H_