Use Ash's ShelfWindowWatcher for app panel windows.

ash/shell/window_watcher_shelf_item_delegate.cc

 // 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.
 
 #include "ash/shell/window_watcher_shelf_item_delegate.h"
 
 #include "ash/shell/window_watcher.h"
 #include "ash/wm/window_util.h"
 #include "ui/aura/window.h"
 
@@ skipping 34 matching lines @@
 }
 
 bool WindowWatcherShelfItemDelegate::CanPin() const {
   return true;
 }
 
 bool WindowWatcherShelfItemDelegate::ShouldShowTooltip() {
   return true;
 }
 
+bool WindowWatcherShelfItemDelegate::IsOpen() const {
+  return true;
+}
+
 void WindowWatcherShelfItemDelegate::Close() {}
 
 }  // namespace shell
 }  // namespace ash