[ash] Add TYPE_DIALOG and its item's LauncherContextMenu

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 35 matching lines @@
 }
 
 bool WindowWatcherShelfItemDelegate::IsDraggable() {
   return true;
 }
 
 bool WindowWatcherShelfItemDelegate::ShouldShowTooltip() {
   return true;
 }
 
+void WindowWatcherShelfItemDelegate::Close() {
+}
+
 }  // namespace shell
 }  // namespace ash