How to add an ionic 2 google login

Done.
1 - Add the plugin
2 - Do some stuff for google dev oAuth

(GitHub - EddyVerbruggen/cordova-plugin-googleplus: ➕ Cordova plugin to login with Google Sign-In on iOS and Android

3 - From .ts file, call the login function

window['plugins'].googleplus.login(
    {
      'scopes': '',
      'webClientId': '',
      'offline': false, 
    },
    function (obj) {
      alert(JSON.stringify(obj)); // do something useful instead of alerting
    },
    function (msg) {
      alert('error: ' + msg);
    }
);