Fetch the user's info from Google.

@returns {Promise} resolves with the user's info.

@protected
function () {
    const url = BASE_URL + '/drive/v2/about?fields=user';
    // requesting user info(mainly for userAdress)
    return this._request('GET', url, {}).then(function (resp){
      try {
        const info = JSON.parse(resp.responseText);
        return Promise.resolve(info);
      } catch (e) {
        return Promise.reject(e);
      }
    });
  }