Login with google - 404 on callback with eventListener()

I am trying to implement login with google in an ionic browser based app. These are the commands I ran to install and create my app:

ionic start tracker sidemenu
cd tracker
cordova plugin add https://git-wip-us.apache.org/repos/asf/cordova-plugin-inappbrowser.git
ionic platform add browser

When I click my login button, the google auth comes up ok. However when the callback is called I get a 404:

Failed to load resource: the server responded with a status of 404 (Not Found)    
http://localhost:8100/callback?code=xxxxxx

This OAuth 2 Ionic example gave this code:

    var clientId = 'xxxxxx-3rpu226qm-xxxxx.apps.googleusercontent.com';
    var scope = 'profile email';
    var ref = window.open('https://accounts.google.com/o/oauth2/auth?client_id=' + clientId +
    '&redirect_uri=http://localhost:8100/callback&scope=https://www.googleapis.com/auth/urlshortener&approval_prompt=force&response_type=code&access_type=offline',
      '_blank', 'location=no');
    ref.addEventListener('loadstart', function (event) {
      console.log('listener event.url: ' + event.url);
      if ((event.url).startsWith("http://localhost:8100/callback")) {
        var requestToken = (event.url).split("code=")[1];
        console.log('request token from google: ' + requestToken);
        ref.close();
      }
    });

Isn’t the eventListener supposed to be catching the callback?

Someone in my stackoverflow thread posted that it’s a known issue in the innappbrowser pluging that loadstart and loaderror aren’t being fired: