With: https://github.com/mozilla/addon-sdk/pull/949/files

page-worker.js

let { events } = require('sdk/content/events');
let { on, emit, off, setListeners } = require('sdk/event/core');
let { filter, pipe, map } = require('sdk/event/utils');
let { create } = require('sdk/frame/utils');
let { window } = require('sdk/addon/window');

let view = create(window.document, {
  nodeName: 'iframe',
  type: 'content',
  uri: 'http://mozilla.org',
  allowJavascript: true,
  allowPlugins: true,
  allowAuth: true
});

let readyEvents = filter(events, function ({type}) {
  return ~['DOMContentLoaded', 'load', 'document-element-inserted'].indexOf(type);
});

on(readyEvents, 'data', function({type, target, data}) {
  console.log('type: ', type, 'target: ', target, 'data: ', data);
});