Gmail Login Ionic - To get Oauth Token

Hi all,
I have integrated gmail login in my app.
I am getting the response after login are displayName,email,familyName,givenName,imageUrl,userId.

I want to also get oauth as well as with the above fields.

My code is
window.plugins.googleplus.login({
//‘scopes’: ‘accessToken’,
//webClientId: “”
}, function (obj) {
console.log(obj);
}