input type="file" doesn't work on Xamarin.Forms Webview (Android)

I have a WebView that points to a website, something like this:

var browser = new WebView {
Source = "www.sometlink.com/uploadimage"
};

This is a html page where it allow users to upload some images. The html element is just a simple:

This works well on iOS, but not on Android. The "Choose File" button does nothing at all (no pop out etc.)

After doing some extensive research, it appears the problem as described here: http://stackoverflow.com/questions/4944102/android-webview-file-input-field-filechooser-doesnt-show-up

The suggested solution works if I switch to Xamarin.Android, but how do I duplicate the solution using Xamarin.Forms?