Google OAuth using LWC + VF

goauth.js

import { LightningElement } from 'lwc';

const BASE_URL='https://accounts.google.com/o/oauth2/v2/auth';

export default class Goauth extends LightningElement {


  doAuth(){

    let client_id='<your client id>';
    console.log('test');
    let redirect_uri=`${window.location.origin}/apex/oauthbroker`;
    let scope='https%3A//www.googleapis.com/auth/drive.metadata.readonly';

    let url=`${BASE_URL}?scope=${scope}&client_id=${client_id}&redirect_uri=${redirect_uri}&response_type=token`;

    window.open(url);

    window.onmessage = msg=>{
      console.log('>> message '+msg.data); //msg.data contains the access token
    }
  }
}

oauthbroker.page

<apex:page>

  <script>
    if(window.location.hash){
            window.opener.postMessage(window.location.hash.substring(1),'<your-lightning-domain>');
    }
  </script>

</apex:page>