How can I upgrade an anonymus user to a google account in firebase?
I tried following the documentation but I don't know how to define googleUser:

var credential = firebase.auth.GoogleAuthProvider.credential(googleUser.getAuthResponse().id_token);

Basically I want the currenly signed in anonymus user to click a sign in with google button, follow the usual google sign in steps upgrading his current anonymus account to the new google one.