chrome: Cleanup class/struct forward declarations

chrome/browser/ui/ash/launcher/arc_app_window_launcher_controller.h

 // Copyright 2016 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_UI_ASH_LAUNCHER_ARC_APP_WINDOW_LAUNCHER_CONTROLLER_H_
 #define CHROME_BROWSER_UI_ASH_LAUNCHER_ARC_APP_WINDOW_LAUNCHER_CONTROLLER_H_
 
 #include <map>
 #include <memory>
 #include <vector>
 
 #include "ash/common/shell_observer.h"
 #include "base/macros.h"
 #include "chrome/browser/ui/app_list/arc/arc_app_list_prefs.h"
 #include "chrome/browser/ui/ash/launcher/app_window_launcher_controller.h"
 #include "mojo/public/cpp/bindings/binding.h"
 #include "ui/aura/env_observer.h"
 #include "ui/aura/window_observer.h"
 
 namespace ash {
 class ShelfDelegate;
 }
 
 namespace aura {
 class Window;
 }
 
-namespace views {
-class Widget;
-}
-
 class ArcAppWindowLauncherItemController;
 class ChromeLauncherController;
 
 class Profile;
 
 class ArcAppWindowLauncherController : public AppWindowLauncherController,
                                        public aura::EnvObserver,
                                        public aura::WindowObserver,
                                        public ash::ShellObserver,
                                        public ArcAppListPrefs::Observer {
@@ skipping 79 matching lines @@
   TaskIdToAppWindowInfo task_id_to_app_window_info_;
   ShelfAppIdToAppControllerMap app_controller_map_;
   std::vector<aura::Window*> observed_windows_;
   Profile* observed_profile_ = nullptr;
   bool observing_shell_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(ArcAppWindowLauncherController);
 };
 
 #endif  // CHROME_BROWSER_UI_ASH_LAUNCHER_ARC_APP_WINDOW_LAUNCHER_CONTROLLER_H_