public class MyDownloadHandler : IDownloadHandler
    {
        public event EventHandler<DownloadItem> OnBeforeDownloadFired;
        public event EventHandler<DownloadItem> OnDownloadUpdatedFired;

        public void OnBeforeDownload(IWebBrowser chromiumWebBrowser,IBrowser browser,DownloadItem downloadItem,IBeforeDownloadCallback callback)
        {
            SharedData.Log.Info(Constants.CONST_TEXT_LOG_DEBUG_DATA + Constants.CONST_TEXT_LOG_DEBUG_DATA_DELIMITER + "CEF OnBeforeDownload : started");
            OnBeforeDownloadFired?.Invoke(this,downloadItem);

            if (!callback.IsDisposed)
            {
                using (callback)
                {
                    callback.Continue(downloadItem.SuggestedFileName,showDialog: true);
                }
            }
            SharedData.Log.Info(Constants.CONST_TEXT_LOG_DEBUG_DATA + Constants.CONST_TEXT_LOG_DEBUG_DATA_DELIMITER + "CEF OnBeforeDownload : ended");
        }

        public void OnDownloadUpdated(IWebBrowser chromiumWebBrowser,IDownloadItemCallback callback)
        {

            SharedData.Log.Info(Constants.CONST_TEXT_LOG_DEBUG_DATA + Constants.CONST_TEXT_LOG_DEBUG_DATA_DELIMITER + "CEF OnDownloadUpdated : started");
            OnDownloadUpdatedFired?.Invoke(this,downloadItem);
 }

显示下载进度条，但没有进行下载，OnBeforeDownload事件不起作用：

public DxLogin(string url)
{
  Cef.Initialize(cefSettings);
  dxloginpage = new ChromiumWebBrowser();
  dxloginpage.DownloadHandler = new MyDownloadHandler();
  InitializeComponent();
  dxloginpage.Address = url;
}