void dispatchPageBackgroundEvent(Route<dynamic> route) {
  if (route == null) {
    return;
  }

  final observers = _listeners[route]?.toList();
  if (observers != null) {
    for (var observer in observers) {
      try {
        observer.onBackground();
      } on Exception catch (e) {
        Logger.log(e.toString());
      }
    }
  }

  Logger.log('page_visibility, '
      '#dispatchPageBackgroundEvent, ${route.settings.name}');

  dispatchGlobalBackgroundEvent(route);
}