public partial class Startup
    {
        public void ConfigureAuth(IAppBuilder app)
        {
            app.CreatePerOwinContext(ApplicationDbContext.Create);
            app.CreatePerOwinContext<ApplicationUserManager>(ApplicationUserManager.Create);
            app.CreatePerOwinContext<ApplicationSignInManager>(ApplicationSignInManager.Create);

            // Enable the application to use a cookie to store information for the signed in user
            // and to use a cookie to temporarily store information about a user logging in with a third party login provider

            app.UseCookieAuthentication(new CookieAuthenticationOptions
            {
                AuthenticationType = DefaultAuthenticationTypes.ApplicationCookie,
                LoginPath = new PathString("/Account/Login"),
            });
              app.UseExternalSignInCookie(DefaultAuthenticationTypes.ExternalCookie);
app.UseTwoFactorSignInCookie(DefaultAuthenticationTypes.TwoFactorCookie, TimeSpan.FromMinutes(5));

app.UseTwoFactorRememberBrowserCookie(DefaultAuthenticationTypes.TwoFactorRememberBrowserCookie);
            app.UseFacebookAuthentication(
               appId: "MeuAppID",
               appSecret: "MeuAppSecret");

            // O que devo setar no FacebookAppId
            // Já Coloquei o Id da app do facebook mas não funcionou

            if (!string.IsNullOrEmpty(ConfigurationManager.AppSettings.Get("FacebookAppId")))
            {
                var facebookOptions = new FacebookAuthenticationOptions
                {
                    AppId = ConfigurationManager.AppSettings.Get(""),
                    AppSecret = ConfigurationManager.AppSettings.Get(""),
                    Provider = new FacebookAuthenticationProvider
                    {
                        OnAuthenticated = (context) =>
                        {
                            context.Identity.AddClaim(new System.Security.Claims.Claim("urn:facebook:access_token", context.AccessToken, XmlSchemaString, "Facebook"));
                            foreach (var x in context.User)
                            {
                                var claimType = string.Format("urn:facebook:{0}", x.Key);
                                string claimValue = x.Value.ToString();
                                if (!context.Identity.HasClaim(claimType, claimValue))
                                    context.Identity.AddClaim(new System.Security.Claims.Claim(claimType, claimValue, XmlSchemaString, "Facebook"));

                            }
                            return Task.FromResult(0);
                        }
                    }
                };
                app.UseFacebookAuthentication(facebookOptions);
            }
        }

        const string XmlSchemaString = "http://www.w3.org/2001/XMLSchema#string";
    }
}