It seems impossible to use session persistence in firebase 3.0.
This was possible in the previous version: https://www.firebase.com/docs/web/guide/login/password.html
authWithPassword() takes an optional third parameter which is an object containing any of the following settings:
remember - String
If not specified - or set to default - sessions are persisted for as long as you have configured in the Login & Auth tab of your App Dashboard. To limit persistence to the lifetime of the current window, set this to sessionOnly. A value of none will not persist authentication data at all and will end authentication as soon as the page is closed.
In version 3.0 there is no mention of the optional 3rd parameter: https://firebase.google.com/docs/reference/js/firebase.auth.Auth#signInWithEmailAndPassword
signInWithEmailAndPassword(email, password)
returns firebase.Promise containing non-null firebase.User
Also, in the new console (https://console.firebase.google.com/) I cannot find the option to change the default persistence.