Turns out that the WebView doesn't provide a way to retrieve its HTML directly. But you can use WebView.InvokeScript like this:
webview.InvokeScript("eval", new string[] {"document.documentElement.outerHTML;"})
You can also obtain the Uri via the LoadCompleted event's NavigationEventArgs.Uri.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…