class ChromeContextMenus extends ChromeApi {
 static final JsObject _contextMenus = chrome['contextMenus'];

 ChromeContextMenus._();

 bool get available => _contextMenus != null;

 /**
  * Creates a new context menu item. Note that if an error occurs during
  * creation, you may not find out until the creation callback fires (the
  * details will be in chrome.runtime.lastError).
  * 
  * [callback] Called when the item has been created in the browser. If there
  * were any problems creating the item, details will be available in
  * chrome.runtime.lastError.
  * 
  * Returns:
  * The ID of the newly created item.
  */
 dynamic create(ContextMenusCreateParams createProperties, [dynamic callback]) {
   if (_contextMenus == null) _throwNotAvailable();

   return _contextMenus.callMethod('create', [jsify(createProperties), jsify(callback)]);
 }

 /**
  * Updates a previously created context menu item.
  * 
  * [id] The ID of the item to update.
  * 
  * [updateProperties] The properties to update. Accepts the same values as the
  * create function.
  */
 Future update(dynamic id, ContextMenusUpdateParams updateProperties) {
   if (_contextMenus == null) _throwNotAvailable();

   var completer = new ChromeCompleter.noArgs();
   _contextMenus.callMethod('update', [jsify(id), jsify(updateProperties), completer.callback]);
   return completer.future;
 }

 /**
  * Removes a context menu item.
  * 
  * [menuItemId] The ID of the context menu item to remove.
  */
 Future remove(dynamic menuItemId) {
   if (_contextMenus == null) _throwNotAvailable();

   var completer = new ChromeCompleter.noArgs();
   _contextMenus.callMethod('remove', [jsify(menuItemId), completer.callback]);
   return completer.future;
 }

 /**
  * Removes all context menu items added by this extension.
  */
 Future removeAll() {
   if (_contextMenus == null) _throwNotAvailable();

   var completer = new ChromeCompleter.noArgs();
   _contextMenus.callMethod('removeAll', [completer.callback]);
   return completer.future;
 }

 /**
  * Fired when a context menu item is clicked.
  */
 Stream<OnClickedEvent> get onClicked => _onClicked.stream;

 final ChromeStreamController<OnClickedEvent> _onClicked =
     new ChromeStreamController<OnClickedEvent>.twoArgs(_contextMenus, 'onClicked', _createOnClickedEvent);

 void _throwNotAvailable() {
   throw new UnsupportedError("'chrome.contextMenus' is not available");
 }
}