Use Ash's ShelfWindowWatcher for app panel windows.

ash/common/test/test_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/common/test/test_shelf_item_delegate.h"
 
 #include "ash/common/wm_lookup.h"
 #include "ash/common/wm_window.h"
 #include "ui/events/event.h"
 #include "ui/views/view.h"
@@ skipping 51 matching lines @@
 }
 
 bool TestShelfItemDelegate::CanPin() const {
   return true;
 }
 
 bool TestShelfItemDelegate::ShouldShowTooltip() {
   return true;
 }
 
+bool TestShelfItemDelegate::IsOpen() const {
+  return window_ != nullptr;
+}
+
 void TestShelfItemDelegate::Close() {}
 
 }  // namespace test
 }  // namespace ash