Use Ash's ShelfWindowWatcher for app panel windows.

ash/shell/window_watcher_shelf_item_delegate.h

 // Copyright 2013 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_SHELL_WINDOW_WATCHER_SHELF_ITEM_DELEGATE_H_
 #define ASH_SHELL_WINDOW_WATCHER_SHELF_ITEM_DELEGATE_H_
 
 #include "ash/common/shelf/shelf_item_delegate.h"
 #include "ash/common/shelf/shelf_item_types.h"
 #include "base/compiler_specific.h"
@@ skipping 11 matching lines @@
   ~WindowWatcherShelfItemDelegate() override;
 
   // ShelfItemDelegate:
   ShelfItemDelegate::PerformedAction ItemSelected(
       const ui::Event& event) override;
   base::string16 GetTitle() override;
   ShelfMenuModel* CreateApplicationMenu(int event_flags) override;
   bool IsDraggable() override;
   bool CanPin() const override;
   bool ShouldShowTooltip() override;
+  bool IsOpen() const override;
   void Close() override;
 
  private:
   ShelfID id_;
   WindowWatcher* watcher_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowWatcherShelfItemDelegate);
 };
 
 }  // namespace shell
 }  // namespace ash
 
 #endif  // ASH_SHELL_WINDOW_WATCHER_SHELF_ITEM_DELEGATE_H_