chromeos: Eliminate WmWindow from //ash/system

ash/system/status_area_widget.h

 // 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.
 
 #ifndef ASH_SYSTEM_STATUS_AREA_WIDGET_H_
 #define ASH_SYSTEM_STATUS_AREA_WIDGET_H_
 
 #include "ash/ash_export.h"
 #include "ash/login_status.h"
 #include "ash/public/cpp/shelf_types.h"
 #include "ash/shelf/shelf_background_animator_observer.h"
 #include "base/macros.h"
 #include "ui/views/widget/widget.h"
 
+namespace aura {
+class Window;
+}
+
 namespace ash {
 class ImeMenuTray;
 class LockScreenActionTray;
 class LogoutButtonTray;
 class OverviewButtonTray;
 class PaletteTray;
 class StatusAreaWidgetDelegate;
 class SystemTray;
 class VirtualKeyboardTray;
 class WebNotificationTray;
 class WmShelf;
-class WmWindow;
 
 class ASH_EXPORT StatusAreaWidget : public views::Widget,
                                     public ShelfBackgroundAnimatorObserver {
  public:
-  StatusAreaWidget(WmWindow* status_container, WmShelf* wm_shelf);
+  StatusAreaWidget(aura::Window* status_container, WmShelf* wm_shelf);
   ~StatusAreaWidget() override;
 
   // Creates the SystemTray, WebNotificationTray and LogoutButtonTray.
   void CreateTrayViews();
 
   // Destroys the system tray and web notification tray. Called before
   // tearing down the windows to avoid shutdown ordering issues.
   void Shutdown();
 
   // Update the alignment of the widget and tray views.
@@ skipping 75 matching lines @@
   LoginStatus login_status_;
 
   WmShelf* wm_shelf_;
 
   DISALLOW_COPY_AND_ASSIGN(StatusAreaWidget);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_STATUS_AREA_WIDGET_H_