Xamarin.Auth - google authentication for firebase

Question

I am trying to use xamarin.auth for authenticating user with their google account. Everything works fine, I get the access token also from google but i get a pop-up that says ** Authentication error - invalid_grant** and it reloads the google sign in page again.

 void OnAuthenticationCompleted(object sender, AuthenticatorCompletedEventArgs e)
    {
        if (e.IsAuthenticated)
        {
            //yay
        }
    }

e.IsAuthenticated is true and the access token is received.

This is the details that i provide to oauth2authenticator instance

private const string ClientId = "mywebappclientid";//auto generated by firebase
    private const string ClientSecret = "mysecret";
    private const string Scope = "https://www.googleapis.com/auth/userinfo.email";
    private const string AuthorizeUrl = "https://accounts.google.com/o/oauth2/auth";
    private const string RedirectUrl ="https://myapp.firebaseapp.com/__/auth/handler";
    private const string AccessTokenUrl = "https://accounts.google.com/o/oauth2/token";