ajax.js

import AjaxService from 'ember-ajax/services/ajax';

export default AjaxService.extend({
  session: Ember.inject.service('session'),
  host: 'http://localhost:8080',

  headers: Ember.computed('session', {
    get() {
      let headers = {};

      this.get('session').authorize('authorizer:application', (headerName, headerValue) => {
        headers[headerName] = headerValue;
      });
      return headers;
    }
  })
});

application.js

import OAuth2Bearer from 'ember-simple-auth/authorizers/oauth2-bearer';

export default OAuth2Bearer.extend();

environment.js

module.exports = function(environment) {
  // ...

  ENV.torii = {
    providers: {
      'google-oauth2-bearer': {
        apiKey: "YOUR-GOOGLE-OAUTH2-API-KEY",
        redirectUri: "http://localhost:4200/oauth2callback"
      }
    }
  };

  // ...
});

torii.js

import Ember from 'ember';
import Torii from 'ember-simple-auth/authenticators/torii';

const { service } = Ember.inject;

export default Torii.extend({
  torii: service('torii'),
  authenticate(options) {
    return this._super(options).then(function (data) {
      return {
        provider: data.provider,
        access_token: data.authorizationToken.access_token
      };
    });
  },
  restore: function(data) {
    return this._super(...arguments).then(() => {
      return data;
    });
  }
});