private IntPtr Create(IntPtr self, IntPtr browser, IntPtr frame, IntPtr schemename, IntPtr request)
 {
     var e = new CreateHandlerEventArgs {
         Browser = Browser.FromHandle(browser),
         Frame = Frame.FromHandle(frame),
         Scheme = StringUtf16.ReadString(schemename)
     };
     return OnCreateHandler(this, e).Handle;
 }
 protected abstract ResourceHandler OnCreateHandler(object sender, CreateHandlerEventArgs e);