How to get back to app after google login

Hi Everyone,

I'm trying to implement google login in my app using xamarin.auth like below

var auth = new OAuth2Authenticator("284202576320-7kgdhaa5sgvkoe03jmmcv0p8lfdma306.apps.googleusercontent.com","cAZW7uegD-h2-
                                                             tNMMf5q1UGQ","https://www.googleapis.com/auth/userinfo.email",new 
                                                             Uri("https://accounts.google.com/o/oauth2/auth"),new 
                                                             Uri("http://dev.myfav.restaurant/Account/LoginComplete"),new 
                                                             Uri("https://accounts.google.com/o/oauth2/token"),null,true)
        {
            AllowCancel = true,                
        };

but Completed event not firing and its going to web page after login i need to get back user to my app how can i achieve this ???? Can anyone help me on this please.

Thanks in advance