CefSharpPost.cs

        public void LoadCustomRequestExample()
        {
            var frame = WebBrowser.GetMainFrame();

            //Create a new request knowing we'd like to use PostData
            var request = frame.CreateRequest(initializePostData:true);
            request.Method = "POST";
            request.Url = "custom://cefsharp/PostDataTest.html";
            request.PostData.AddData("test=123&data=456");

            frame.LoadRequest(request);
        }