tenfourfox/b2g/chrome/content/shell.js

/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- /
/* vim: set shiftwidth=2 tabstop=2 autoindent cindent expandtab: */
/* 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/. */

window.performance.mark('gecko-shell-loadstart');

Cu.import('resource://gre/modules/ContactService.jsm');
Cu.import('resource://gre/modules/DataStoreChangeNotifier.jsm');
Cu.import('resource://gre/modules/AlarmService.jsm');
Cu.import('resource://gre/modules/ActivitiesService.jsm');
Cu.import('resource://gre/modules/NotificationDB.jsm');
Cu.import('resource://gre/modules/Payment.jsm');
Cu.import("resource://gre/modules/AppsUtils.jsm");
Cu.import('resource://gre/modules/UserAgentOverrides.jsm');
Cu.import('resource://gre/modules/Keyboard.jsm');
Cu.import('resource://gre/modules/ErrorPage.jsm');
Cu.import('resource://gre/modules/AlertsHelper.jsm');
Cu.import('resource://gre/modules/RequestSyncService.jsm');
Cu.import('resource://gre/modules/SystemUpdateService.jsm');

if (isGonk) {
  Cu.import('resource://gre/modules/MultiscreenHandler.jsm');
  Cu.import('resource://gre/modules/NetworkStatsService.jsm');
  Cu.import('resource://gre/modules/ResourceStatsService.jsm');
}

Cu.import('resource://gre/modules/KillSwitchMain.jsm');

// Identity
Cu.import('resource://gre/modules/SignInToWebsite.jsm');
SignInToWebsiteController.init();

Cu.import('resource://gre/modules/FxAccountsMgmtService.jsm');
Cu.import('resource://gre/modules/DownloadsAPI.jsm');
Cu.import('resource://gre/modules/MobileIdentityManager.jsm');
Cu.import('resource://gre/modules/PresentationDeviceInfoManager.jsm');
Cu.import('resource://gre/modules/AboutServiceWorkers.jsm');

XPCOMUtils.defineLazyModuleGetter(this, "SystemAppProxy",
                                  "resource://gre/modules/SystemAppProxy.jsm");

XPCOMUtils.defineLazyModuleGetter(this, "Screenshot",
                                  "resource://gre/modules/Screenshot.jsm");

Cu.import('resource://gre/modules/Webapps.jsm');
DOMApplicationRegistry.allAppsLaunchable = true;

XPCOMUtils.defineLazyServiceGetter(Services, 'env',
                                   '@mozilla.org/process/environment;1',
                                   'nsIEnvironment');

XPCOMUtils.defineLazyServiceGetter(Services, 'ss',
                                   '@mozilla.org/content/style-sheet-service;1',
                                   'nsIStyleSheetService');

XPCOMUtils.defineLazyServiceGetter(this, 'gSystemMessenger',
                                   '@mozilla.org/system-message-internal;1',
                                   'nsISystemMessagesInternal');

XPCOMUtils.defineLazyGetter(this, "ppmm", function() {
  return Cc["@mozilla.org/parentprocessmessagemanager;1"]
         .getService(Ci.nsIMessageListenerManager);
});

if (isGonk) {
  XPCOMUtils.defineLazyGetter(this, "libcutils", function () {
    Cu.import("resource://gre/modules/systemlibs.js");
    return libcutils;
  });
}

XPCOMUtils.defineLazyServiceGetter(Services, 'captivePortalDetector',
                                  '@mozilla.org/toolkit/captive-detector;1',
                                  'nsICaptivePortalDetector');

if (AppConstants.MOZ_SAFE_BROWSING) {
  XPCOMUtils.defineLazyModuleGetter(this, "SafeBrowsing",
                "resource://gre/modules/SafeBrowsing.jsm");
}

XPCOMUtils.defineLazyModuleGetter(this, "SafeMode",
                                  "resource://gre/modules/SafeMode.jsm");

window.performance.measure('gecko-shell-jsm-loaded', 'gecko-shell-loadstart');

function debug(str) {
  dump(' -*- Shell.js: ' + str + '\n');
}

const once = event => {
  let target = shell.contentBrowser;
  return new Promise((resolve, reject) => {
    target.addEventListener(event, function gotEvent(evt) {
      target.removeEventListener(event, gotEvent, false);
      resolve(evt);
    }, false);
  });
}

function clearCache() {
  let cache = Cc["@mozilla.org/netwerk/cache-storage-service;1"]
                .getService(Ci.nsICacheStorageService);
  cache.clear();
}

function clearCacheAndReload() {
  // Reload the main frame with a cleared cache.
  debug('Reloading ' + shell.contentBrowser.contentWindow.location);
  clearCache();
  shell.contentBrowser.contentWindow.location.reload(true);
  once('mozbrowserlocationchange').then(
    evt => {
      shell.sendEvent(window, "ContentStart");
    });
}

function restart() {
  let appStartup = Cc['@mozilla.org/toolkit/app-startup;1']
                     .getService(Ci.nsIAppStartup);
  appStartup.quit(Ci.nsIAppStartup.eForceQuit | Ci.nsIAppStartup.eRestart);
}

function debugCrashReport(aStr) {
  AppConstants.MOZ_CRASHREPORTER && dump('Crash reporter : ' + aStr);
}

var shell = {

  get CrashSubmit() {
    delete this.CrashSubmit;
    if (AppConstants.MOZ_CRASHREPORTER) {
      Cu.import("resource://gre/modules/CrashSubmit.jsm", this);
      return this.CrashSubmit;
    } else {
      dump('Crash reporter : disabled at build time.');
      return this.CrashSubmit = null;
    }
  },

  onlineForCrashReport: function shell_onlineForCrashReport() {
    let wifiManager = navigator.mozWifiManager;
    let onWifi = (wifiManager &&
                  (wifiManager.connection.status == 'connected'));
    return !Services.io.offline && onWifi;
  },

  reportCrash: function shell_reportCrash(isChrome, aCrashID) {
    let crashID = aCrashID;
    try {
      // For chrome crashes, we want to report the lastRunCrashID.
      if (isChrome) {
        crashID = Cc["@mozilla.org/xre/app-info;1"]
                    .getService(Ci.nsIXULRuntime).lastRunCrashID;
      }
    } catch(e) {
      debugCrashReport('Failed to fetch crash id. Crash ID is "' + crashID
                       + '" Exception: ' + e);
    }

    // Bail if there isn't a valid crashID.
    if (!this.CrashSubmit || !crashID && !this.CrashSubmit.pendingIDs().length) {
      return;
    }

    // purge the queue.
    this.CrashSubmit.pruneSavedDumps();

    // check for environment affecting crash reporting
    let env = Cc["@mozilla.org/process/environment;1"]
                .getService(Ci.nsIEnvironment);
    let shutdown = env.get("MOZ_CRASHREPORTER_SHUTDOWN");
    if (shutdown) {
      let appStartup = Cc["@mozilla.org/toolkit/app-startup;1"]
                         .getService(Ci.nsIAppStartup);
      appStartup.quit(Ci.nsIAppStartup.eForceQuit);
    }

    let noReport = env.get("MOZ_CRASHREPORTER_NO_REPORT");
    if (noReport) {
      return;
    }

    try {
      // Check if we should automatically submit this crash.
      if (Services.prefs.getBoolPref('app.reportCrashes')) {
        this.submitCrash(crashID);
      } else {
        this.deleteCrash(crashID);
      }
    } catch (e) {
      debugCrashReport('Can\'t fetch app.reportCrashes. Exception: ' + e);
    }

    // We can get here if we're just submitting old pending crashes.
    // Check that there's a valid crashID so that we only notify the
    // user if a crash just happened and not when we OOM. Bug 829477
    if (crashID) {
      this.sendChromeEvent({
        type: "handle-crash",
        crashID: crashID,
        chrome: isChrome
      });
    }
  },

  deleteCrash: function shell_deleteCrash(aCrashID) {
    if (aCrashID) {
      debugCrashReport('Deleting pending crash: ' + aCrashID);
      shell.CrashSubmit.delete(aCrashID);
    }
  },

  // this function submit the pending crashes.
  // make sure you are online.
  submitQueuedCrashes: function shell_submitQueuedCrashes() {
    // submit the pending queue.
    let pending = shell.CrashSubmit.pendingIDs();
    for (let crashid of pending) {
      debugCrashReport('Submitting crash: ' + crashid);
      shell.CrashSubmit.submit(crashid);
    }
  },

  // This function submits a crash when we're online.
  submitCrash: function shell_submitCrash(aCrashID) {
    if (this.onlineForCrashReport()) {
      this.submitQueuedCrashes();
      return;
    }

    debugCrashReport('Not online, postponing.');

    Services.obs.addObserver(function observer(subject, topic, state) {
      let network = subject.QueryInterface(Ci.nsINetworkInfo);
      if (network.state == Ci.nsINetworkInfo.NETWORK_STATE_CONNECTED
          && network.type == Ci.nsINetworkInfo.NETWORK_TYPE_WIFI) {
        shell.submitQueuedCrashes();

        Services.obs.removeObserver(observer, topic);
      }
    }, "network-connection-state-changed", false);
  },

  get homeURL() {
    try {
      let homeSrc = Services.env.get('B2G_HOMESCREEN');
      if (homeSrc)
        return homeSrc;
    } catch (e) {}

    return Services.prefs.getCharPref('b2g.system_startup_url');
  },

  get manifestURL() {
    return Services.prefs.getCharPref('b2g.system_manifest_url');
  },

  _started: false,
  hasStarted: function shell_hasStarted() {
    return this._started;
  },

  bootstrap: function() {
    if (AppConstants.MOZ_B2GDROID) {
      Cc["@mozilla.org/b2g/b2gdroid-setup;1"]
        .getService(Ci.nsIObserver).observe(window, "shell-startup", null);
    }

    window.performance.mark('gecko-shell-bootstrap');

    // Before anything, check if we want to start in safe mode.
    SafeMode.check(window).then(() => {
      let startManifestURL =
        Cc['@mozilla.org/commandlinehandler/general-startup;1?type=b2gbootstrap']
          .getService(Ci.nsISupports).wrappedJSObject.startManifestURL;

      // If --start-manifest hasn't been specified, we re-use the latest specified manifest.
      // If it's the first launch, we will fallback to b2g.default.start_manifest_url
      if (AppConstants.MOZ_GRAPHENE && !startManifestURL) {
        try {
          startManifestURL = Services.prefs.getCharPref("b2g.system_manifest_url");
        } catch(e) {}
      }

      if (!startManifestURL) {
        try {
          startManifestURL = Services.prefs.getCharPref("b2g.default.start_manifest_url");
        } catch(e) {}
      }

      if (startManifestURL) {
        Cu.import('resource://gre/modules/Bootstraper.jsm');

        if (AppConstants.MOZ_GRAPHENE && Bootstraper.isInstallRequired(startManifestURL)) {
          // Installing the app my take some time. We don't want to keep the
          // native window hidden.
          showInstallScreen();
        }

        Bootstraper.ensureSystemAppInstall(startManifestURL)
                   .then(this.start.bind(this))
                   .catch(Bootstraper.bailout);
      } else {
        this.start();
      }
    });
  },

  start: function shell_start() {
    window.performance.mark('gecko-shell-start');
    this._started = true;

    // This forces the initialization of the cookie service before we hit the
    // network.
    // See bug 810209
    let cookies = Cc["@mozilla.org/cookieService;1"];

    try {
      let cr = Cc["@mozilla.org/xre/app-info;1"]
                 .getService(Ci.nsICrashReporter);
      // Dogfood id. We might want to remove it in the future.
      // see bug 789466
      try {
        let dogfoodId = Services.prefs.getCharPref('prerelease.dogfood.id');
        if (dogfoodId != "") {
          cr.annotateCrashReport("Email", dogfoodId);
        }
      }
      catch (e) { }

      if (isGonk) {
        // Annotate crash report
        let annotations = [ [ "Android_Hardware",     "ro.hardware" ],
                            [ "Android_Device",       "ro.product.device" ],
                            [ "Android_CPU_ABI2",     "ro.product.cpu.abi2" ],
                            [ "Android_CPU_ABI",      "ro.product.cpu.abi" ],
                            [ "Android_Manufacturer", "ro.product.manufacturer" ],
                            [ "Android_Brand",        "ro.product.brand" ],
                            [ "Android_Model",        "ro.product.model" ],
                            [ "Android_Board",        "ro.product.board" ],
          ];

        annotations.forEach(function (element) {
            cr.annotateCrashReport(element[0], libcutils.property_get(element[1]));
          });

        let androidVersion = libcutils.property_get("ro.build.version.sdk") +
                             "(" + libcutils.property_get("ro.build.version.codename") + ")";
        cr.annotateCrashReport("Android_Version", androidVersion);

        SettingsListener.observe("deviceinfo.os", "", function(value) {
          try {
            let cr = Cc["@mozilla.org/xre/app-info;1"]
                       .getService(Ci.nsICrashReporter);
            cr.annotateCrashReport("B2G_OS_Version", value);
          } catch(e) { }
        });
      }
    } catch(e) {
      debugCrashReport('exception: ' + e);
    }

    let homeURL = this.homeURL;
    if (!homeURL) {
      let msg = 'Fatal error during startup: No homescreen found: try setting B2G_HOMESCREEN';
      alert(msg);
      return;
    }
    let manifestURL = this.manifestURL;
    // <html:iframe id="systemapp"
    //              mozbrowser="true" allowfullscreen="true"
    //              style="overflow: hidden; height: 100%; width: 100%; border: none;"
    //              src="data:text/html;charset=utf-8,%3C!DOCTYPE html>%3Cbody style='background:black;'>"/>
    let systemAppFrame =
      document.createElementNS('http://www.w3.org/1999/xhtml', 'html:iframe');
    systemAppFrame.setAttribute('id', 'systemapp');
    systemAppFrame.setAttribute('mozbrowser', 'true');
    systemAppFrame.setAttribute('mozapp', manifestURL);
    systemAppFrame.setAttribute('allowfullscreen', 'true');
    systemAppFrame.setAttribute('src', 'blank.html');
    let container = document.getElementById('container');

    if (AppConstants.platform == 'macosx') {
      // See shell.html
      let hotfix = document.getElementById('placeholder');
      if (hotfix) {
        container.removeChild(hotfix);
      }
    }

    this.contentBrowser = container.appendChild(systemAppFrame);

    let webNav = systemAppFrame.contentWindow
                               .QueryInterface(Ci.nsIInterfaceRequestor)
                               .getInterface(Ci.nsIWebNavigation);
    webNav.sessionHistory = Cc["@mozilla.org/browser/shistory;1"].createInstance(Ci.nsISHistory);

    if (AppConstants.MOZ_GRAPHENE) {
      webNav.QueryInterface(Ci.nsIDocShell).windowDraggingAllowed = true;
    }

    let audioChannels = systemAppFrame.allowedAudioChannels;
    audioChannels && audioChannels.forEach(function(audioChannel) {
      // Set all audio channels as unmuted by default
      // because some audio in System app will be played
      // before AudioChannelService[1] is Gaia is loaded.
      // [1]: https://github.com/mozilla-b2g/gaia/blob/master/apps/system/js/audio_channel_service.js
      audioChannel.setMuted(false);
    });

    // On firefox mulet, shell.html is loaded in a tab
    // and we have to listen on the chrome event handler
    // to catch key events
    let chromeEventHandler = window.QueryInterface(Ci.nsIInterfaceRequestor)
                                   .getInterface(Ci.nsIWebNavigation)
                                   .QueryInterface(Ci.nsIDocShell)
                                   .chromeEventHandler || window;
    // Capture all key events so we can filter out hardware buttons
    // And send them to Gaia via mozChromeEvents.
    // Ideally, hardware buttons wouldn't generate key events at all, or
    // if they did, they would use keycodes that conform to DOM 3 Events.
    // See discussion in https://bugzilla.mozilla.org/show_bug.cgi?id=762362
    chromeEventHandler.addEventListener('keydown', this, true);
    chromeEventHandler.addEventListener('keyup', this, true);

    window.addEventListener('MozApplicationManifest', this);
    window.addEventListener('MozAfterPaint', this);
    window.addEventListener('sizemodechange', this);
    window.addEventListener('unload', this);
    this.contentBrowser.addEventListener('mozbrowserloadstart', this, true);
    this.contentBrowser.addEventListener('mozbrowserselectionstatechanged', this, true);
    this.contentBrowser.addEventListener('mozbrowserscrollviewchange', this, true);
    this.contentBrowser.addEventListener('mozbrowsercaretstatechanged', this);

    CustomEventManager.init();
    WebappsHelper.init();
    UserAgentOverrides.init();
    CaptivePortalLoginHelper.init();

    this.contentBrowser.src = homeURL;
    this._isEventListenerReady = false;

    window.performance.mark('gecko-shell-system-frame-set');

    ppmm.addMessageListener("content-handler", this);
    ppmm.addMessageListener("dial-handler", this);
    ppmm.addMessageListener("sms-handler", this);
    ppmm.addMessageListener("mail-handler", this);
    ppmm.addMessageListener("file-picker", this);

    if (AppConstants.MOZ_SAFE_BROWSING) {
      setTimeout(function() {
        SafeBrowsing.init();
      }, 5000);
    }
  },

  stop: function shell_stop() {
    window.removeEventListener('unload', this);
    window.removeEventListener('keydown', this, true);
    window.removeEventListener('keyup', this, true);
    window.removeEventListener('MozApplicationManifest', this);
    window.removeEventListener('sizemodechange', this);
    this.contentBrowser.removeEventListener('mozbrowserloadstart', this, true);
    this.contentBrowser.removeEventListener('mozbrowserselectionstatechanged', this, true);
    this.contentBrowser.removeEventListener('mozbrowserscrollviewchange', this, true);
    this.contentBrowser.removeEventListener('mozbrowsercaretstatechanged', this);
    ppmm.removeMessageListener("content-handler", this);

    UserAgentOverrides.uninit();
  },

  // If this key event represents a hardware button which needs to be send as
  // a message, broadcasts it with the message set to 'xxx-button-press' or
  // 'xxx-button-release'.
  broadcastHardwareKeys: function shell_broadcastHardwareKeys(evt) {
    let type;
    let message;

    let mediaKeys = {
      'MediaTrackNext': 'media-next-track-button',
      'MediaTrackPrevious': 'media-previous-track-button',
      'MediaPause': 'media-pause-button',
      'MediaPlay': 'media-play-button',
      'MediaPlayPause': 'media-play-pause-button',
      'MediaStop': 'media-stop-button',
      'MediaRewind': 'media-rewind-button',
      'MediaFastForward': 'media-fast-forward-button'
    };

    if (evt.keyCode == evt.DOM_VK_F1) {
      type = 'headset-button';
      message = 'headset-button';
    } else if (mediaKeys[evt.key]) {
      type = 'media-button';
      message = mediaKeys[evt.key];
    } else {
      return;
    }

    switch (evt.type) {
      case 'keydown':
        message = message + '-press';
        break;
      case 'keyup':
        message = message + '-release';
        break;
    }

    // Let applications receive the headset button and media key press/release message.
    if (message !== this.lastHardwareButtonMessage) {
      this.lastHardwareButtonMessage = message;
      gSystemMessenger.broadcastMessage(type, message);
    }
  },

  lastHardwareButtonMessage: null, // property for the hack above
  visibleNormalAudioActive: false,

  handleEvent: function shell_handleEvent(evt) {
    function checkReloadKey() {
      if (evt.type !== 'keyup') {
        return false;
      }

      try {
        let key = JSON.parse(Services.prefs.getCharPref('b2g.reload_key'));
        return (evt.keyCode  == key.key   &&
                evt.ctrlKey  == key.ctrl  &&
                evt.altKey   == key.alt   &&
                evt.shiftKey == key.shift &&
                evt.metaKey  == key.meta);
      } catch(e) {
        debug('Failed to get key: ' + e);
      }

      return false;
    }

    let content = this.contentBrowser.contentWindow;
    switch (evt.type) {
      case 'keydown':
      case 'keyup':
        if (checkReloadKey()) {
          clearCacheAndReload();
        } else {
          this.broadcastHardwareKeys(evt);
        }
        break;
      case 'sizemodechange':
        if (window.windowState == window.STATE_MINIMIZED && !this.visibleNormalAudioActive) {
          this.contentBrowser.setVisible(false);
        } else {
          this.contentBrowser.setVisible(true);
        }
        break;
      case 'load':
        if (content.document.location == 'about:blank') {
          return;
        }
        content.removeEventListener('load', this, true);
        this.notifyContentWindowLoaded();
        break;
      case 'mozbrowserloadstart':
        if (content.document.location == 'about:blank') {
          this.contentBrowser.addEventListener('mozbrowserlocationchange', this, true);
          return;
        }

        this.notifyContentStart();
        break;
      case 'mozbrowserlocationchange':
        if (content.document.location == 'about:blank') {
          return;
        }

        this.notifyContentStart();
       break;
      case 'mozbrowserscrollviewchange':
        this.sendChromeEvent({
          type: 'scrollviewchange',
          detail: evt.detail,
        });
        break;
      case 'mozbrowserselectionstatechanged':
        // The mozbrowserselectionstatechanged event, may have crossed the chrome-content boundary.
        // This event always dispatch to shell.js. But the offset we got from this event is
        // based on tab's coordinate. So get the actual offsets between shell and evt.target.
        let elt = evt.target;
        let win = elt.ownerDocument.defaultView;
        let offsetX = win.mozInnerScreenX - window.mozInnerScreenX;
        let offsetY = win.mozInnerScreenY - window.mozInnerScreenY;

        let rect = elt.getBoundingClientRect();
        offsetX += rect.left;
        offsetY += rect.top;

        let data = evt.detail;
        data.offsetX = offsetX;
        data.offsetY = offsetY;

        DoCommandHelper.setEvent(evt);
        shell.sendChromeEvent({
          type: 'selectionstatechanged',
          detail: data,
        });
        break;
      case 'mozbrowsercaretstatechanged':
        {
          let elt = evt.target;
          let win = elt.ownerDocument.defaultView;
          let offsetX = win.mozInnerScreenX - window.mozInnerScreenX;
          let offsetY = win.mozInnerScreenY - window.mozInnerScreenY;

          let rect = elt.getBoundingClientRect();
          offsetX += rect.left;
          offsetY += rect.top;

          let data = evt.detail;
          data.offsetX = offsetX;
          data.offsetY = offsetY;
          data.sendDoCommandMsg = null;

          shell.sendChromeEvent({
            type: 'caretstatechanged',
            detail: data,
          });
        }
        break;

      case 'MozApplicationManifest':
        try {
          if (!Services.prefs.getBoolPref('browser.cache.offline.enable'))
            return;

          let contentWindow = evt.originalTarget.defaultView;
          let documentElement = contentWindow.document.documentElement;
          if (!documentElement)
            return;

          let manifest = documentElement.getAttribute('manifest');
          if (!manifest)
            return;

          let principal = contentWindow.document.nodePrincipal;
          if (Services.perms.testPermissionFromPrincipal(principal, 'offline-app') == Ci.nsIPermissionManager.UNKNOWN_ACTION) {
            if (Services.prefs.getBoolPref('browser.offline-apps.notify')) {
              // FIXME Bug 710729 - Add a UI for offline cache notifications
              return;
            }
            return;
          }

          Services.perms.addFromPrincipal(principal, 'offline-app',
                                          Ci.nsIPermissionManager.ALLOW_ACTION);

          let documentURI = Services.io.newURI(contentWindow.document.documentURI,
                                               null,
                                               null);
          let manifestURI = Services.io.newURI(manifest, null, documentURI);
          let updateService = Cc['@mozilla.org/offlinecacheupdate-service;1']
                              .getService(Ci.nsIOfflineCacheUpdateService);
          updateService.scheduleUpdate(manifestURI, documentURI, principal, window);
        } catch (e) {
          dump('Error while creating offline cache: ' + e + '\n');
        }
        break;
      case 'MozAfterPaint':
        window.removeEventListener('MozAfterPaint', this);
        // This event should be sent before System app returns with
        // system-message-listener-ready mozContentEvent, because it's on
        // the critical launch path of the app.
        SystemAppProxy._sendCustomEvent('mozChromeEvent', {
          type: 'system-first-paint'
        }, /* noPending */ true);
        break;
      case 'unload':
        this.stop();
        break;
    }
  },

  // Send an event to a specific window, document or element.
  sendEvent: function shell_sendEvent(target, type, details) {
    if (target === this.contentBrowser) {
      // We must ask SystemAppProxy to send the event in this case so
      // that event would be dispatched from frame.contentWindow instead of
      // on the System app frame.
      SystemAppProxy._sendCustomEvent(type, details);
      return;
    }

    let doc = target.document || target.ownerDocument || target;
    let event = doc.createEvent('CustomEvent');
    event.initCustomEvent(type, true, true, details ? details : {});
    target.dispatchEvent(event);
  },

  sendCustomEvent: function shell_sendCustomEvent(type, details) {
    SystemAppProxy._sendCustomEvent(type, details);
  },

  sendChromeEvent: function shell_sendChromeEvent(details) {
    this.sendCustomEvent("mozChromeEvent", details);
  },

  receiveMessage: function shell_receiveMessage(message) {
    var activities = { 'content-handler': { name: 'view', response: null },
                       'dial-handler':    { name: 'dial', response: null },
                       'mail-handler':    { name: 'new',  response: null },
                       'sms-handler':     { name: 'new',  response: null },
                       'file-picker':     { name: 'pick', response: 'file-picked' } };

    if (!(message.name in activities))
      return;

    let data = message.data;
    let activity = activities[message.name];

    let a = new MozActivity({
      name: activity.name,
      data: data
    });

    if (activity.response) {
      a.onsuccess = function() {
        let sender = message.target.QueryInterface(Ci.nsIMessageSender);
        sender.sendAsyncMessage(activity.response, { success: true,
                                                     result:  a.result });
      }
      a.onerror = function() {
        let sender = message.target.QueryInterface(Ci.nsIMessageSender);
        sender.sendAsyncMessage(activity.response, { success: false });
      }
    }
  },

  notifyContentStart: function shell_notifyContentStart() {
    window.performance.mark('gecko-shell-notify-content-start');
    this.contentBrowser.removeEventListener('mozbrowserloadstart', this, true);
    this.contentBrowser.removeEventListener('mozbrowserlocationchange', this, true);

    let content = this.contentBrowser.contentWindow;
    content.addEventListener('load', this, true);

    this.reportCrash(true);

    SystemAppProxy.registerFrame(shell.contentBrowser);

    this.sendEvent(window, 'ContentStart');

    Services.obs.notifyObservers(null, 'content-start', null);

    isGonk && Cu.import('resource://gre/modules/OperatorApps.jsm');

    if (AppConstants.MOZ_GRAPHENE &&
        Services.prefs.getBoolPref("b2g.nativeWindowGeometry.fullscreen")) {
      window.fullScreen = true;
    }

    shell.handleCmdLine();
  },

  handleCmdLine: function() {
    // This isn't supported on devices.
    if (!isGonk && !AppConstants.MOZ_B2GDROID) {
      let b2gcmds = Cc["@mozilla.org/commandlinehandler/general-startup;1?type=b2gcmds"]
                      .getService(Ci.nsISupports);
      let args = b2gcmds.wrappedJSObject.cmdLine;
      try {
        // Returns null if -url is not present.
        let url = args.handleFlagWithParam("url", false);
        if (url) {
          this.sendChromeEvent({type: "mozbrowseropenwindow", url});
          args.preventDefault = true;
        }
      } catch(e) {
        // Throws if -url is present with no params.
      }
    }
  },

  // This gets called when window.onload fires on the System app content window,
  // which means things in <html> are parsed and statically referenced <script>s
  // and <script defer>s are loaded and run.
  notifyContentWindowLoaded: function shell_notifyContentWindowLoaded() {
    isGonk && libcutils.property_set('sys.boot_completed', '1');

    // This will cause Gonk Widget to remove boot animation from the screen
    // and reveals the page.
    Services.obs.notifyObservers(null, "browser-ui-startup-complete", "");

    SystemAppProxy.setIsLoaded();
  },

  // This gets called when the content sends us system-message-listener-ready
  // mozContentEvent, OR when an observer message tell us we should consider
  // the content as ready.
  notifyEventListenerReady: function shell_notifyEventListenerReady() {
    if (this._isEventListenerReady) {
      Cu.reportError('shell.js: SystemApp has already been declared as being ready.');
      return;
    }
    this._isEventListenerReady = true;

    if (Services.prefs.getBoolPref('b2g.orientation.animate')) {
      Cu.import('resource://gre/modules/OrientationChangeHandler.jsm');
    }

    SystemAppProxy.setIsReady();
  }
};

Services.obs.addObserver(function onFullscreenOriginChange(subject, topic, data) {
  shell.sendChromeEvent({ type: "fullscreenoriginchange",
                          fullscreenorigin: data });
}, "fullscreen-origin-change", false);

DOMApplicationRegistry.registryReady.then(function () {
  // This event should be sent before System app returns with
  // system-message-listener-ready mozContentEvent, because it's on
  // the critical launch path of the app.
  SystemAppProxy._sendCustomEvent('mozChromeEvent', {
    type: 'webapps-registry-ready'
  }, /* noPending */ true);
});

Services.obs.addObserver(function onBluetoothVolumeChange(subject, topic, data) {
  shell.sendChromeEvent({
    type: "bluetooth-volumeset",
    value: data
  });
}, 'bluetooth-volume-change', false);

Services.obs.addObserver(function(subject, topic, data) {
  shell.sendCustomEvent('mozmemorypressure');
}, 'memory-pressure', false);

Services.obs.addObserver(function(subject, topic, data) {
  shell.notifyEventListenerReady();
}, 'system-message-listener-ready', false);

var permissionMap = new Map([
  ['unknown', Services.perms.UNKNOWN_ACTION],
  ['allow', Services.perms.ALLOW_ACTION],
  ['deny', Services.perms.DENY_ACTION],
  ['prompt', Services.perms.PROMPT_ACTION],
]);
var permissionMapRev = new Map(Array.from(permissionMap.entries()).reverse());

var CustomEventManager = {
  init: function custevt_init() {
    window.addEventListener("ContentStart", (function(evt) {
      let content = shell.contentBrowser.contentWindow;
      content.addEventListener("mozContentEvent", this, false, true);
    }).bind(this), false);
  },

  handleEvent: function custevt_handleEvent(evt) {
    let detail = evt.detail;
    dump('XXX FIXME : Got a mozContentEvent: ' + detail.type + "\n");

    switch(detail.type) {
      case 'webapps-install-granted':
      case 'webapps-install-denied':
      case 'webapps-uninstall-granted':
      case 'webapps-uninstall-denied':
        WebappsHelper.handleEvent(detail);
        break;
      case 'select-choicechange':
        FormsHelper.handleEvent(detail);
        break;
      case 'system-message-listener-ready':
        Services.obs.notifyObservers(null, 'system-message-listener-ready', null);
        break;
      case 'captive-portal-login-cancel':
        CaptivePortalLoginHelper.handleEvent(detail);
        break;
      case 'inputmethod-update-layouts':
      case 'inputregistry-add':
      case 'inputregistry-remove':
        KeyboardHelper.handleEvent(detail);
        break;
      case 'do-command':
        DoCommandHelper.handleEvent(detail.cmd);
        break;
      case 'copypaste-do-command':
        Services.obs.notifyObservers({ wrappedJSObject: shell.contentBrowser },
                                     'ask-children-to-execute-copypaste-command', detail.cmd);
        break;
      case 'add-permission':
        Services.perms.add(Services.io.newURI(detail.uri, null, null),
                           detail.permissionType, permissionMap.get(detail.permission));
        break;
      case 'remove-permission':
        Services.perms.remove(Services.io.newURI(detail.uri, null, null),
                              detail.permissionType);
        break;
      case 'test-permission':
        let result = Services.perms.testExactPermission(
          Services.io.newURI(detail.uri, null, null), detail.permissionType);
        // Not equal check here because we want to prevent default only if it's not set
        if (result !== permissionMapRev.get(detail.permission)) {
          evt.preventDefault();
        }
        break;
      case 'shutdown-application':
        let appStartup = Cc['@mozilla.org/toolkit/app-startup;1']
                           .getService(Ci.nsIAppStartup);
        appStartup.quit(appStartup.eAttemptQuit);
        break;
      case 'toggle-fullscreen-native-window':
        window.fullScreen = !window.fullScreen;
        Services.prefs.setBoolPref("b2g.nativeWindowGeometry.fullscreen",
                                   window.fullScreen);
        break;
      case 'minimize-native-window':
        window.minimize();
        break;
      case 'clear-cache-and-reload':
        clearCacheAndReload();
        break;
      case 'clear-cache-and-restart':
        clearCache();
        restart();
        break;
      case 'restart':
        restart();
        break;
    }
  }
}

var DoCommandHelper = {
  _event: null,
  setEvent: function docommand_setEvent(evt) {
    this._event = evt;
  },

  handleEvent: function docommand_handleEvent(cmd) {
    if (this._event) {
      Services.obs.notifyObservers({ wrappedJSObject: this._event.target },
                                   'copypaste-docommand', cmd);
      this._event = null;
    }
  }
}

var WebappsHelper = {
  _installers: {},
  _count: 0,

  init: function webapps_init() {
    Services.obs.addObserver(this, "webapps-launch", false);
    Services.obs.addObserver(this, "webapps-ask-install", false);
    Services.obs.addObserver(this, "webapps-ask-uninstall", false);
    Services.obs.addObserver(this, "webapps-close", false);
  },

  registerInstaller: function webapps_registerInstaller(data) {
    let id = "installer" + this._count++;
    this._installers[id] = data;
    return id;
  },

  handleEvent: function webapps_handleEvent(detail) {
    if (!detail || !detail.id)
      return;

    let installer = this._installers[detail.id];
    delete this._installers[detail.id];
    switch (detail.type) {
      case "webapps-install-granted":
        DOMApplicationRegistry.confirmInstall(installer);
        break;
      case "webapps-install-denied":
        DOMApplicationRegistry.denyInstall(installer);
        break;
      case "webapps-uninstall-granted":
        DOMApplicationRegistry.confirmUninstall(installer);
        break;
      case "webapps-uninstall-denied":
        DOMApplicationRegistry.denyUninstall(installer);
        break;
    }
  },

  observe: function webapps_observe(subject, topic, data) {
    let json = JSON.parse(data);
    json.mm = subject;

    let id;

    switch(topic) {
      case "webapps-launch":
        DOMApplicationRegistry.getManifestFor(json.manifestURL).then((aManifest) => {
          if (!aManifest)
            return;

          let manifest = new ManifestHelper(aManifest, json.origin,
                                            json.manifestURL);
          let payload = {
            timestamp: json.timestamp,
            url: manifest.fullLaunchPath(json.startPoint),
            manifestURL: json.manifestURL
          };
          shell.sendCustomEvent("webapps-launch", payload);
        });
        break;
      case "webapps-ask-install":
        id = this.registerInstaller(json);
        shell.sendChromeEvent({
          type: "webapps-ask-install",
          id: id,
          app: json.app
        });
        break;
      case "webapps-ask-uninstall":
        id = this.registerInstaller(json);
        shell.sendChromeEvent({
          type: "webapps-ask-uninstall",
          id: id,
          app: json.app
        });
        break;
      case "webapps-close":
        shell.sendCustomEvent("webapps-close", {
          "manifestURL": json.manifestURL
        });
        break;
    }
  }
}

var KeyboardHelper = {
  handleEvent: function keyboard_handleEvent(detail) {
    switch (detail.type) {
      case 'inputmethod-update-layouts':
        Keyboard.setLayouts(detail.layouts);

        break;
      case 'inputregistry-add':
      case 'inputregistry-remove':
        Keyboard.inputRegistryGlue.returnMessage(detail);

        break;
    }
  }
};

// This is the backend for Gaia's screenshot feature.  Gaia requests a
// screenshot by sending a mozContentEvent with detail.type set to
// 'take-screenshot'.  Then we take a screenshot and send a
// mozChromeEvent with detail.type set to 'take-screenshot-success'
// and detail.file set to the an image/png blob
window.addEventListener('ContentStart', function ss_onContentStart() {
  let content = shell.contentBrowser.contentWindow;
  content.addEventListener('mozContentEvent', function ss_onMozContentEvent(e) {
    if (e.detail.type !== 'take-screenshot')
      return;

    try {
      shell.sendChromeEvent({
        type: 'take-screenshot-success',
        file: Screenshot.get()
      });
    } catch (e) {
      dump('exception while creating screenshot: ' + e + '\n');
      shell.sendChromeEvent({
        type: 'take-screenshot-error',
        error: String(e)
      });
    }
  });
});

(function contentCrashTracker() {
  Services.obs.addObserver(function(aSubject, aTopic, aData) {
      let props = aSubject.QueryInterface(Ci.nsIPropertyBag2);
      if (props.hasKey("abnormal") && props.hasKey("dumpID")) {
        shell.reportCrash(false, props.getProperty("dumpID"));
      }
    },
    "ipc:content-shutdown", false);
})();

var CaptivePortalLoginHelper = {
  init: function init() {
    Services.obs.addObserver(this, 'captive-portal-login', false);
    Services.obs.addObserver(this, 'captive-portal-login-abort', false);
    Services.obs.addObserver(this, 'captive-portal-login-success', false);
  },
  handleEvent: function handleEvent(detail) {
    Services.captivePortalDetector.cancelLogin(detail.id);
  },
  observe: function observe(subject, topic, data) {
    shell.sendChromeEvent(JSON.parse(data));
  }
}

// Listen for crashes submitted through the crash reporter UI.
window.addEventListener('ContentStart', function cr_onContentStart() {
  let content = shell.contentBrowser.contentWindow;
  content.addEventListener("mozContentEvent", function cr_onMozContentEvent(e) {
    if (e.detail.type == "submit-crash" && e.detail.crashID) {
      debugCrashReport("submitting crash at user request ", e.detail.crashID);
      shell.submitCrash(e.detail.crashID);
    } else if (e.detail.type == "delete-crash" && e.detail.crashID) {
      debugCrashReport("deleting crash at user request ", e.detail.crashID);
      shell.deleteCrash(e.detail.crashID);
    }
  });
});

window.addEventListener('ContentStart', function update_onContentStart() {
  Cu.import('resource://gre/modules/WebappsUpdater.jsm');
  WebappsUpdater.handleContentStart(shell);

  if (!AppConstants.MOZ_UPDATER) {
    return;
  }

  let promptCc = Cc["@mozilla.org/updates/update-prompt;1"];
  if (!promptCc) {
    return;
  }

  let updatePrompt = promptCc.createInstance(Ci.nsIUpdatePrompt);
  if (!updatePrompt) {
    return;
  }

  updatePrompt.wrappedJSObject.handleContentStart(shell);
});

(function geolocationStatusTracker() {
  let gGeolocationActive = false;

  Services.obs.addObserver(function(aSubject, aTopic, aData) {
    let oldState = gGeolocationActive;
    if (aData == "starting") {
      gGeolocationActive = true;
    } else if (aData == "shutdown") {
      gGeolocationActive = false;
    }

    if (gGeolocationActive != oldState) {
      shell.sendChromeEvent({
        type: 'geolocation-status',
        active: gGeolocationActive
      });
    }
}, "geolocation-device-events", false);
})();

(function headphonesStatusTracker() {
  Services.obs.addObserver(function(aSubject, aTopic, aData) {
    shell.sendChromeEvent({
      type: 'headphones-status-changed',
      state: aData
    });
}, "headphones-status-changed", false);
})();

(function audioChannelChangedTracker() {
  Services.obs.addObserver(function(aSubject, aTopic, aData) {
    shell.sendChromeEvent({
      type: 'audio-channel-changed',
      channel: aData
    });
}, "audio-channel-changed", false);
})();

(function defaultVolumeChannelChangedTracker() {
  Services.obs.addObserver(function(aSubject, aTopic, aData) {
    shell.sendChromeEvent({
      type: 'default-volume-channel-changed',
      channel: aData
    });
}, "default-volume-channel-changed", false);
})();

(function visibleAudioChannelChangedTracker() {
  Services.obs.addObserver(function(aSubject, aTopic, aData) {
    shell.sendChromeEvent({
      type: 'visible-audio-channel-changed',
      channel: aData
    });
    shell.visibleNormalAudioActive = (aData == 'normal');
}, "visible-audio-channel-changed", false);
})();

(function recordingStatusTracker() {
  // Recording status is tracked per process with following data structure:
  // {<processId>: {<requestURL>: {isApp: <isApp>,
  //                               count: <N>,
  //                               audioCount: <N>,
  //                               videoCount: <N>}}
  let gRecordingActiveProcesses = {};

  let recordingHandler = function(aSubject, aTopic, aData) {
    let props = aSubject.QueryInterface(Ci.nsIPropertyBag2);
    let processId = (props.hasKey('childID')) ? props.get('childID')
                                              : 'main';
    if (processId && !gRecordingActiveProcesses.hasOwnProperty(processId)) {
      gRecordingActiveProcesses[processId] = {};
    }

    let commandHandler = function (requestURL, command) {
      let currentProcess = gRecordingActiveProcesses[processId];
      let currentActive = currentProcess[requestURL];
      let wasActive = (currentActive['count'] > 0);
      let wasAudioActive = (currentActive['audioCount'] > 0);
      let wasVideoActive = (currentActive['videoCount'] > 0);

      switch (command.type) {
        case 'starting':
          currentActive['count']++;
          currentActive['audioCount'] += (command.isAudio) ? 1 : 0;
          currentActive['videoCount'] += (command.isVideo) ? 1 : 0;
          break;
        case 'shutdown':
          currentActive['count']--;
          currentActive['audioCount'] -= (command.isAudio) ? 1 : 0;
          currentActive['videoCount'] -= (command.isVideo) ? 1 : 0;
          break;
        case 'content-shutdown':
          currentActive['count'] = 0;
          currentActive['audioCount'] = 0;
          currentActive['videoCount'] = 0;
          break;
      }

      if (currentActive['count'] > 0) {
        currentProcess[requestURL] = currentActive;
      } else {
        delete currentProcess[requestURL];
      }

      // We need to track changes if any active state is changed.
      let isActive = (currentActive['count'] > 0);
      let isAudioActive = (currentActive['audioCount'] > 0);
      let isVideoActive = (currentActive['videoCount'] > 0);
      if ((isActive != wasActive) ||
          (isAudioActive != wasAudioActive) ||
          (isVideoActive != wasVideoActive)) {
        shell.sendChromeEvent({
          type: 'recording-status',
          active: isActive,
          requestURL: requestURL,
          isApp: currentActive['isApp'],
          isAudio: isAudioActive,
          isVideo: isVideoActive
        });
      }
    };

    switch (aData) {
      case 'starting':
      case 'shutdown':
        // create page record if it is not existed yet.
        let requestURL = props.get('requestURL');
        if (requestURL &&
            !gRecordingActiveProcesses[processId].hasOwnProperty(requestURL)) {
          gRecordingActiveProcesses[processId][requestURL] = {isApp: props.get('isApp'),
                                                              count: 0,
                                                              audioCount: 0,
                                                              videoCount: 0};
        }
        commandHandler(requestURL, { type: aData,
                                     isAudio: props.get('isAudio'),
                                     isVideo: props.get('isVideo')});
        break;
      case 'content-shutdown':
        // iterate through all the existing active processes
        Object.keys(gRecordingActiveProcesses[processId]).forEach(function(requestURL) {
          commandHandler(requestURL, { type: aData,
                                       isAudio: true,
                                       isVideo: true});
        });
        break;
    }

    // clean up process record if no page record in it.
    if (Object.keys(gRecordingActiveProcesses[processId]).length == 0) {
      delete gRecordingActiveProcesses[processId];
    }
  };
  Services.obs.addObserver(recordingHandler, 'recording-device-events', false);
  Services.obs.addObserver(recordingHandler, 'recording-device-ipc-events', false);

  Services.obs.addObserver(function(aSubject, aTopic, aData) {
    // send additional recording events if content process is being killed
    let processId = aSubject.QueryInterface(Ci.nsIPropertyBag2).get('childID');
    if (gRecordingActiveProcesses.hasOwnProperty(processId)) {
      Services.obs.notifyObservers(aSubject, 'recording-device-ipc-events', 'content-shutdown');
    }
  }, 'ipc:content-shutdown', false);
})();

(function volumeStateTracker() {
  Services.obs.addObserver(function(aSubject, aTopic, aData) {
    shell.sendChromeEvent({
      type: 'volume-state-changed',
      active: (aData == 'Shared')
    });
}, 'volume-state-changed', false);
})();

if (isGonk) {
  // Devices don't have all the same partition size for /cache where we
  // store the http cache.
  (function setHTTPCacheSize() {
    let path = Services.prefs.getCharPref("browser.cache.disk.parent_directory");
    let volumeService = Cc["@mozilla.org/telephony/volume-service;1"]
                          .getService(Ci.nsIVolumeService);

    let stats = volumeService.createOrGetVolumeByPath(path).getStats();

    // We must set the size in KB, and keep a bit of free space.
    let size = Math.floor(stats.totalBytes / 1024) - 1024;

    // keep the default value if it is smaller than the physical partition size.
    let oldSize = Services.prefs.getIntPref("browser.cache.disk.capacity");
    if (size < oldSize) {
      Services.prefs.setIntPref("browser.cache.disk.capacity", size);
    }
  })();

  try {
    let gmpService = Cc["@mozilla.org/gecko-media-plugin-service;1"]
                       .getService(Ci.mozIGeckoMediaPluginChromeService);
    gmpService.addPluginDirectory("/system/b2g/gmp-clearkey/0.1");
  } catch(e) {
    dump("Failed to add clearkey path! " + e + "\n");
  }
}

// Calling this observer will cause a shutdown an a profile reset.
// Use eg. : Services.obs.notifyObservers(null, 'b2g-reset-profile', null);
Services.obs.addObserver(function resetProfile(subject, topic, data) {
  Services.obs.removeObserver(resetProfile, topic);

  // Listening for 'profile-before-change2' which is late in the shutdown
  // sequence, but still has xpcom access.
  Services.obs.addObserver(function clearProfile(subject, topic, data) {
    Services.obs.removeObserver(clearProfile, topic);
    if (isGonk) {
      let json = Cc['@mozilla.org/file/local;1'].createInstance(Ci.nsIFile);
      json.initWithPath('/system/b2g/webapps/webapps.json');
      let toRemove = json.exists()
        // This is a user build, just rm -r /data/local /data/b2g/mozilla
        ? ['/data/local', '/data/b2g/mozilla']
        // This is an eng build. We clear the profile and a set of files
        // under /data/local.
        : ['/data/b2g/mozilla',
           '/data/local/permissions.sqlite',
           '/data/local/storage',
           '/data/local/OfflineCache'];

      toRemove.forEach(function(dir) {
        try {
          let file = Cc['@mozilla.org/file/local;1'].createInstance(Ci.nsIFile);
          file.initWithPath(dir);
          file.remove(true);
        } catch(e) { dump(e); }
      });
    } else {
      // Desktop builds.
      let profile = Services.dirsvc.get('ProfD', Ci.nsIFile);

      // We don't want to remove everything from the profile, since this
      // would prevent us from starting up.
      let whitelist = ['defaults', 'extensions', 'settings.json',
                       'user.js', 'webapps'];
      let enumerator = profile.directoryEntries;
      while (enumerator.hasMoreElements()) {
        let file = enumerator.getNext().QueryInterface(Ci.nsIFile);
        if (whitelist.indexOf(file.leafName) == -1) {
          file.remove(true);
        }
      }
    }
  },
  'profile-before-change2', false);

  let appStartup = Cc['@mozilla.org/toolkit/app-startup;1']
                     .getService(Ci.nsIAppStartup);
  appStartup.quit(Ci.nsIAppStartup.eForceQuit);
}, 'b2g-reset-profile', false);

if (AppConstants.MOZ_GRAPHENE) {
  const restoreWindowGeometry = () => {
    let screenX = Services.prefs.getIntPref("b2g.nativeWindowGeometry.screenX");
    let screenY = Services.prefs.getIntPref("b2g.nativeWindowGeometry.screenY");
    let width = Services.prefs.getIntPref("b2g.nativeWindowGeometry.width");
    let height = Services.prefs.getIntPref("b2g.nativeWindowGeometry.height");

    if (screenX == -1) {
      // Center
      screenX = (screen.width - width) / 2;
      screenY = (screen.height - height) / 2;
    }

    moveTo(screenX, screenY);
    resizeTo(width, height);
  }
  restoreWindowGeometry();

  const saveWindowGeometry = () => {
    window.removeEventListener("unload", saveWindowGeometry);
    Services.prefs.setIntPref("b2g.nativeWindowGeometry.screenX", screenX);
    Services.prefs.setIntPref("b2g.nativeWindowGeometry.screenY", screenY);
    Services.prefs.setIntPref("b2g.nativeWindowGeometry.width", outerWidth);
    Services.prefs.setIntPref("b2g.nativeWindowGeometry.height", outerHeight);
  }
  window.addEventListener("unload", saveWindowGeometry);

  var baseWindow = window.QueryInterface(Ci.nsIInterfaceRequestor)
                         .getInterface(Ci.nsIWebNavigation)
                         .QueryInterface(Ci.nsIDocShellTreeItem)
                         .treeOwner
                         .QueryInterface(Ci.nsIInterfaceRequestor)
                         .getInterface(Ci.nsIBaseWindow);

  const showNativeWindow = () => baseWindow.visibility = true;
  const hideNativeWindow = () => baseWindow.visibility = false;

  const showInstallScreen = () => {
    const grapheneStrings =
      Services.strings.createBundle('chrome://b2g-l10n/locale/graphene.properties');
    document.querySelector('#installing > .message').textContent =
      grapheneStrings.GetStringFromName('installing');
    showNativeWindow();
  }

  const hideInstallScreen = () => {
    document.body.classList.add('content-loaded');
  }

  window.addEventListener('ContentStart', () => {
    shell.contentBrowser.contentWindow.addEventListener('load', () => {
      hideInstallScreen();
      showNativeWindow();
    });
  });

  hideNativeWindow();
}