public class CefSharpCommonObject
  {
    public dynamic Start()
    {
      var response = dummyProc.Start();

      return new
      {
        response.IsSuccess
      };
    }

    public dynamic Stop()
    {
      var response = dummyProc.Stop();

      return new
      {
        response.IsSuccess
      };
    }
  }

cefBrowser.JavascriptObjectRepository.Register("jsCommunicator", new CefSharpCommonObject(), true);

<script type="text/javascript">
    (async () => {
      await CefSharp.BindObjectAsync("jsCommunicator", "jsTest");

      jsCommunicator.start().then(() => {
      }, () => {
      });

      setTimeout(jsCommunicator.stop, 5000);
    })();
  </script>