class ChromeCommands extends ChromeApi {
 static final JsObject _commands = chrome['commands'];

 ChromeCommands._();

 bool get available => _commands != null;

 /**
  * Returns all the registered extension commands for this extension and their
  * shortcut (if active).
  */
 Future<List<Command>> getAll() {
   if (_commands == null) _throwNotAvailable();

   var completer = new ChromeCompleter<List<Command>>.oneArg((e) => listify(e, _createCommand));
   _commands.callMethod('getAll', [completer.callback]);
   return completer.future;
 }

 /**
  * Fired when a registered command is activated using a keyboard shortcut.
  */
 Stream<String> get onCommand => _onCommand.stream;

 final ChromeStreamController<String> _onCommand =
     new ChromeStreamController<String>.oneArg(_commands, 'onCommand', selfConverter);

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