public CefReturnValue OnBeforeResourceLoad(IWebBrowser browserControl, IBrowser browser, IFrame frame, IRequest request, IRequestCallback callback)
    {
        var headers = request.Headers;
        headers["Custom-Header"] = "My Custom Header";
        request.Headers = headers;
        return CefReturnValue.Continue;

    }

    private void /*Btn*/Sceenshot_Click(object sender, RoutedEventArgs e)
    {
/*
        //CefSharp - Quick and Dirty Screenshot with no class dependency
        MessageBox.Show("Take screenshot");
        double dWidth = (webCefSharpChromiumWebBrowser.ActualWidth);
        double dHeight = (webCefSharpChromiumWebBrowser.ActualHeight);
        int actualWidth = 0;
        int actualHeight = 0;
        actualWidth = Convert.ToInt32(dWidth);
        actualHeight = Convert.ToInt32(dHeight);
        RenderTargetBitmap renderTargetBitmap = new RenderTargetBitmap(actualWidth, actualHeight, 90, 90, PixelFormats.Pbgra32);
        renderTargetBitmap.Render(webCefSharpChromiumWebBrowser);
        PngBitmapEncoder pngImage = new PngBitmapEncoder();
        pngImage.Frames.Add(BitmapFrame.Create(renderTargetBitmap));
        using (Stream fileStream = File.Create(@"C:\SaveFolderName\apollo.png")) //uses System.IO for fileStream
        {
            pngImage.Save(fileStream);
        }
*/
    }

 /*Here is an example that reuses the image that's already rendered to the screen.*/


var template = Browser.Template;
var image = (System.Windows.Controls.Image)template.FindName("PART_image", Browser);
var pngImage = new PngBitmapEncoder();

pngImage.Frames.Add(BitmapFrame.Create((System.Windows.Media.Imaging.BitmapSource)image.Source));

var screenshotPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "CefSharp screenshot" + DateTime.Now.Ticks + ".png");

using (var fileStream = File.Create(screenshotPath))
{
    pngImage.Save(fileStream);
}