使用 HttpRequestMessage 導航

設定自定義使用者代理並導航到 Uri：

var userAgent = "my custom user agent";
var uri = new Uri("http://useragentstring.com/");
var requestMessage = new HttpRequestMessage(HttpMethod.Get, uri);
requestMessage.Headers.Add("User-Agent", userAgent);

this.webView.NavigateWithHttpRequestMessage(requestMessage);