Get Google API credentials from GNOME Online Accounts

google.py

import gi

gi.require_version('Goa', '1.0')

from gi.repository import Goa

def main(args):
    client = Goa.Client.new_sync (None)
    accounts = client.get_accounts ()

    for obj in accounts:
        account = obj.get_account ()
        if account.props.provider_name == "Google":
            oauth2 = obj.get_oauth2_based ()
            break

    if oauth2 is None:
        sys.exit ()


    print (oauth2.props.client_id)
    print (oauth2.props.client_secret)
    print (oauth2.call_get_access_token_sync(None))

    return 0

if __name__ == '__main__':
    import sys
    sys.exit(main(sys.argv))