The Tor Browser / file revision

 /* This Source Code Form is subject to the terms of the Mozilla Public

  * License, v. 2.0. If a copy of the MPL was not distributed with this

  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

 'use strict';

 const { Class } = require('../core/heritage');

 const { BrowserWindow } = require('../window/browser');

 const { WindowTracker } = require('../deprecated/window-utils');

 const { isBrowser, getMostRecentBrowserWindow } = require('../window/utils');

 const { windowNS } = require('../window/namespace');

 const { on, off, once, emit } = require('../event/core');

 const { method } = require('../lang/functional');

 const { EventTarget } = require('../event/target');

 const { List, addListItem } = require('../util/list');

 const ERR_FENNEC_MSG = 'This method is not yet supported by Fennec, consider using require("sdk/tabs") instead';

 // NOTE: On Fennec there is only one window.

 let BrowserWindows = Class({

   implements: [ List ],

   extends: EventTarget,

   initialize: function() {

     List.prototype.initialize.apply(this);

   },

   get activeWindow() {

     let window = getMostRecentBrowserWindow();

     return window ? getBrowserWindow({window: window}) : null;

   },

   open: function open(options) {

     throw new Error(ERR_FENNEC_MSG);

     return null;

   }

 });

 const browserWindows = exports.browserWindows = BrowserWindows();

 /**

  * Gets a `BrowserWindow` for the given `chromeWindow` if previously

  * registered, `null` otherwise.

  */

 function getRegisteredWindow(chromeWindow) {

   for each (let window in browserWindows) {

     if (chromeWindow === windowNS(window).window)

       return window;

   }

   return null;

 }

 /**

  * Gets a `BrowserWindow` for the provided window options obj

  * @params {Object} options

  *    Options that are passed to the the `BrowserWindowTrait`

  * @returns {BrowserWindow}

  */

 function getBrowserWindow(options) {

   let window = null;

   // if we have a BrowserWindow already then use it

   if ('window' in options)

     window = getRegisteredWindow(options.window);

   if (window)

     return window;

   // we don't have a BrowserWindow yet, so create one

   var window = BrowserWindow(options);

   addListItem(browserWindows, window);

   return window;

 }

 WindowTracker({

   onTrack: function onTrack(chromeWindow) {

     if (!isBrowser(chromeWindow)) return;

     let window = getBrowserWindow({ window: chromeWindow });

     emit(browserWindows, 'open', window);

   },

   onUntrack: function onUntrack(chromeWindow) {

     if (!isBrowser(chromeWindow)) return;

     let window = getBrowserWindow({ window: chromeWindow });

     emit(browserWindows, 'close', window);

   }

 });