In AngularFire you were able to access the providers (e.g Google) accessToken for the authenticated user.
There does not seem to be a way to access this with AngularFire
With AngularFire2, you can get the token like this :
this.af.auth.getToken() // returns a firebase.Promise
If you want to get an ES6 Promise instead, just use
Promise.resolve() .then(() => this.af.auth.getToken() as Promise)