WebClient.DownloadFile() のタイムアウトを実装するにはどうすればよいですか?

<code class="language-csharp">public class WebDownload : WebClient
{
    /// <summary>
    /// Timeout in milliseconds
    /// </summary>
    public int Timeout { get; set; }

    public WebDownload() : this(60000) { } // Default 60-second timeout

    public WebDownload(int timeout)
    {
        this.Timeout = timeout;
    }

    protected override WebRequest GetWebRequest(Uri address)
    {
        WebRequest request = base.GetWebRequest(address);
        if (request != null)
        {
            request.Timeout = this.Timeout;
        }
        return request;
    }
}</code>

<code class="language-csharp">using (WebDownload client = new WebDownload(10000)) // 10-second timeout
{
    client.DownloadFile("http://example.com/file.zip", "file.zip");
}</code>