Google plus authentication Windows Phone

    void GooglePlusLoginPage_Loaded(object sender, RoutedEventArgs e)
            {
                var url = "https://accounts.google.com/o/oauth2/auth?response_type=code&redirect_uri=" + RedirctedUri + "&scope=https://www.googleapis.com/auth/plus.login%20https://www.googleapis.com/auth/plus.me%20https://www.googleapis.com/auth/userinfo.email%20https://www.googleapis.com/auth/userinfo.profile&client_id=" + ClientId;
                webBrowserGooglePlusLogin.IsScriptEnabled = true;
                webBrowserGooglePlusLogin.Navigate(new Uri(url, UriKind.RelativeOrAbsolute));

            }

            private void webBrowserGooglePlusLogin_Navigated(object sender, System.Windows.Navigation.NavigationEventArgs e)
            {
                webBrowserGooglePlusLogin.Visibility = Visibility.Visible;
            }

            private void webBrowserGooglePlusLogin_Navigating(object sender, NavigatingEventArgs e)
            {
                if (e.Uri.Host.Equals("localhost"))
                {
                    webBrowserGooglePlusLogin.Visibility = Visibility.Collapsed;

                    e.Cancel = true;
                    int pos = e.Uri.Query.IndexOf("=");

                    //get the access code
                    string messageCode = pos > -1 ? e.Uri.Query.Substring(pos + 1) : null;

                    //when code is not equeals to null get the access token
                    if (messageCode != null)
                    {
                        //get the access token
                        Parameters = "code=" + messageCode + "&client_id=" + ClientId + "&client_secret=" + ClientSecret + "&redirect_uri=" + RedirctedUri + "&grant_type=authorization_code";
                        HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create("https://accounts.google.com/o/oauth2/token");
                        webRequest.Method = "POST";
                        webRequest.ContentType = "application/x-www-form-urlencoded";

                        // Start web request
                        webRequest.BeginGetRequestStream(new AsyncCallback(GetRequestStreamCallback), webRequest);
                    }
                }
            }

            void GetRequestStreamCallback(IAsyncResult asynchronousResult)
            {
                try
                {
                    HttpWebRequest webRequest = (HttpWebRequest)asynchronousResult.AsyncState;
                    // End the stream request operation
                    Stream postStream = webRequest.EndGetRequestStream(asynchronousResult);


                    byte[] byteArray = Encoding.UTF8.GetBytes(Parameters);

                    // Add the post data to the web request
                    postStream.Write(byteArray, 0, byteArray.Length);
                    postStream.Close();

                    // Start the web request
                    webRequest.BeginGetResponse(new AsyncCallback(GetResponseCallback), webRequest);
                }
                catch (WebException ex)
                {
                }

            }

            void GetResponseCallback(IAsyncResult asynchronousResult)
            {
                try
                {
                    var request = (HttpWebRequest)asynchronousResult.AsyncState;
                    using (var resp = (HttpWebResponse)request.EndGetResponse(asynchronousResult))
                    {
                        using (var streamResponse = resp.GetResponseStream())
                        {
                            var GooglePlusSerializerData = new DataContractJsonSerializer(typeof(GooglePlusAccessToken));
                            var GooglePlusProfileData = GooglePlusSerializerData.ReadObject(streamResponse) as GooglePlusAccessToken;
                            this.Dispatcher.BeginInvoke(
                                (Action<GooglePlusAccessToken>)((GooglePlusUserData) =>
                                {

                                    //save the response
                                    thisApp.AccessToken = googlePlusTokens.AccessToken = GooglePlusUserData.AccessToken;
                                    thisApp.LoggedBy = "Google+";
                                    googlePlusTokens.RefreshToken = GooglePlusUserData.RefreshToken;
                                    googlePlusTokens.ExpiresIn = GooglePlusUserData.ExpiresIn;
                                    googlePlusTokens.TokenType = GooglePlusUserData.TokenType;


                                    // request user profile
                                    //RequestForUserProfile();
                                    NavigationService.GoBack();

                                }), GooglePlusProfileData);

                        }
                    }
                }
                catch (WebException ex)
                {

                }
            }