protected override void OnElementChanged(ElementChangedEventArgs <Xamarin.Forms.WebView> e)
 {
     base.OnElementChanged(e);
     cvw            = (CoreWebView)e.NewElement;
     cvw.CreatePDF += SavePDFMethod;
     NativeView     = this.Control;
 }
 protected override void OnElementChanged(VisualElementChangedEventArgs e)
 {
     base.OnElementChanged(e);
     cvw            = (CoreWebView)e.NewElement;
     cvw.CreatePDF += SavePDFMethod;
 }