Separate the logic of popup alignment and workarea handling as delegate.

ash/system/web_notification/web_notification_tray.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_WEB_NOTIFICATION_WEB_NOTIFICATION_TRAY_H_
 #define ASH_SYSTEM_WEB_NOTIFICATION_WEB_NOTIFICATION_TRAY_H_
 
 #include "ash/ash_export.h"
 #include "ash/system/tray/tray_background_view.h"
 #include "ash/system/user/login_status.h"
@@ skipping 23 matching lines @@
 class MessageBubbleBase;
 class MessageCenter;
 class MessageCenterBubble;
 class MessagePopupCollection;
 }
 
 namespace ash {
 class StatusAreaWidget;
 class WebNotificationBubbleWrapper;
 class WebNotificationButton;
-class WorkAreaObserver;
+class AshPopupAlignmentDelegate;
 
 class ASH_EXPORT WebNotificationTray
     : public TrayBackgroundView,
       public views::TrayBubbleView::Delegate,
       public message_center::MessageCenterTrayDelegate,
       public views::ButtonListener,
       public base::SupportsWeakPtr<WebNotificationTray>,
       public ui::SimpleMenuModel::Delegate {
  public:
   explicit WebNotificationTray(StatusAreaWidget* status_area_widget);
@@ skipping 113 matching lines @@
   bool show_message_center_on_unlock_;
 
   bool should_update_tray_content_;
 
   // True when the shelf auto hide behavior has to be blocked. Previously
   // this was done by checking |message_center_bubble_| but actually
   // the check can be called when creating this object, so it would cause
   // flickers of the shelf from hidden to shown. See: crbug.com/181213
   bool should_block_shelf_auto_hide_;
 
-  // Observes the work area for |popup_collection_| and notifies to it.
-  scoped_ptr<WorkAreaObserver> work_area_observer_;
+  scoped_ptr<AshPopupAlignmentDelegate> popup_alignment_delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(WebNotificationTray);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_WEB_NOTIFICATION_WEB_NOTIFICATION_TRAY_H_