[Aura] Initial app list webui.

chrome/browser/resources/ntp4/page_list_view.js

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/**
+ * @fileoverview PageListView implementation.
+ * PageListView manages page list, dot list, switcher buttons and glue apps
+ * pages with backend.
+ */
+
+cr.define('ntp4', function() {
+  'use strict';
+
+  /**
+   * Object for accessing localized strings.
+   * @type {!LocalStrings}
+   */
+  var localStrings = new LocalStrings;
+
+  /**
+   * Current live PageListView instance.
+   * @type {!Object|undefined}
+   */
+  var instance;

[Evan Stade, 2011/11/07 23:59:20]

I don't like the restriction that this class should only be used as a singleton.
The static functions that rely on |instance| are all pass-throughs, so it's not
too bad to duplicate them into each place (Aura, NewTab) that wants the
singleton use case.

[xiyuan, 2011/11/08 21:09:18]

Done.

+
+  /**
+   * Creates a PageListView object.
+   * @constructor
+   * @extends {Object}
+   */
+  function PageListView() {
+  }
+
+  PageListView.getInstance = function() {
+    return instance;
+  }
+
+  PageListView.prototype = {
+    /**
+     * The CardSlider object to use for changing app pages.
+     * @type {CardSlider|undefined}
+     */
+    cardSlider: undefined,
+
+    /**
+     * The frame div for cardSlider.
+     * @type {!Element|undefined}
+     */
+    sliderFrame: undefined,
+
+    /**
+     * The 'page-list' element.
+     * @type {!Element|undefined}
+     */
+    pageList: undefined,
+
+    /**
+     * A list of all 'tile-page' elements.
+     * @type {!NodeList|undefined}
+     */
+    tilePages: undefined,
+
+    /**
+     * A list of all 'apps-page' elements.
+     * @type {!NodeList|undefined}
+     */
+    appsPages: undefined,
+
+    /**
+     * The Most Visited page.
+     * @type {!Element|undefined}
+     */
+    mostVisitedPage: undefined,
+
+    /**
+     * The Bookmarks page.
+     * @type {!Element|undefined}
+     */
+    bookmarksPage: undefined,
+
+    /**
+     * The 'dots-list' element.
+     * @type {!Element|undefined}
+     */
+    dotList: undefined,
+
+    /**
+     * The left and right paging buttons.
+     * @type {!Element|undefined}
+     */
+    pageSwitcherStart: undefined,
+    pageSwitcherEnd: undefined,
+
+    /**
+     * The 'trash' element.  Note that technically this is unnecessary,
+     * JavaScript creates the object for us based on the id.  But I don't want
+     * to rely on the ID being the same, and JSCompiler doesn't know about it.
+     * @type {!Element|undefined}
+     */
+    trash: undefined,
+
+    /**
+     * The type of page that is currently shown. The value is a numerical ID.
+     * @type {number}
+     */
+    shownPage: 0,
+
+    /**
+     * The index of the page that is currently shown, within the page type.
+     * For example if the third Apps page is showing, this will be 2.
+     * @type {number}
+     */
+    shownPageIndex: 0,
+
+    /**
+     * EventTracker for managing event listeners for page events.
+     * @type {!EventTracker}
+     */
+    eventTracker: new EventTracker,
+
+    /**
+     * If non-null, this is the ID of the app to highlight to the user the next
+     * time getAppsCallback runs. "Highlight" in this case means to switch to
+     * the page and run the new tile animation.
+     * @type {String}
+     */
+    highlightAppId: null,
+
+    /**
+     * Initializes page list view.
+     */
+    initialize: function() {
+      instance = this;
+
+      this.pageList = getRequiredElement('page-list');
+
+      this.dotList = getRequiredElement('dot-list');
+      cr.ui.decorate(this.dotList, ntp4.DotList);
+
+      this.trash = getRequiredElement('trash');
+      new ntp4.Trash(this.trash);
+
+      this.pageSwitcherStart = $('page-switcher-start');
+      if (this.pageSwitcherStart)
+        ntp4.initializePageSwitcher(this.pageSwitcherStart);
+
+      this.pageSwitcherEnd = $('page-switcher-end');
+      if (this.pageSwitcherEnd)
+        ntp4.initializePageSwitcher(this.pageSwitcherEnd);
+
+      this.shownPage = templateData['shown_page_type'];
+      this.shownPageIndex = templateData['shown_page_index'];
+
+      // Request data on the apps so we can fill them in.
+      // Note that this is kicked off asynchronously.  'getAppsCallback' will be
+      // invoked at some point after this function returns.
+      chrome.send('getApps');
+
+      document.addEventListener('keydown', this.onDocKeyDown.bind(this));
+      // Prevent touch events from triggering any sort of native scrolling
+      document.addEventListener('touchmove', function(e) {
+        e.preventDefault();
+      }, true);
+
+      this.tilePages = this.pageList.getElementsByClassName('tile-page');
+      this.appsPages = this.pageList.getElementsByClassName('apps-page');
+
+      // Initialize the cardSlider without any cards at the moment
+      this.sliderFrame = getRequiredElement('card-slider-frame');
+      this.cardSlider = new CardSlider(this.sliderFrame, this.pageList,
+          this.sliderFrame.offsetWidth);
+      this.cardSlider.initialize();
+
+      // Ensure the slider is resized appropriately with the window
+      window.addEventListener('resize', this.onWindowResize_.bind(this));
+
+      // Handle the page being changed
+      this.pageList.addEventListener(
+          CardSlider.EventType.CARD_CHANGED,
+          this.cardChangedHandler.bind(this));
+    },
+
+    /**
+     * Appends a tile page (for bookmarks or most visited).
+     *
+     * @param {TilePage} page The page element.
+     * @param {string} title The title of the tile page.
+     * @param {bool} titleIsEditable If true, the title can be changed.
+     * @param {TilePage} opt_refNode Optional reference node to insert in front
+     * of.
+     * When opt_refNode is falsey, |page| will just be appended to the end of
+     * the page list.
+     */
+    appendTilePage: function(page, title, titleIsEditable, opt_refNode) {
+      // If no opt_refNode given, use bookmarksPage (if any).
+      if (!opt_refNode)
+        opt_refNode = this.bookmarksPage;
+
+      // When opt_refNode is falsey, insertBefore acts just like appendChild.
+      this.pageList.insertBefore(page, opt_refNode);
+
+      // Remember special MostVisitedPage and BookmarksPage.
+      if (typeof ntp4.MostVisitedPage != 'undefined' &&
+          page instanceof ntp4.MostVisitedPage) {
+        assert(this.tilePages.length == 1,
+               'MostVisitedPage should be added as first tile page');
+        this.mostVisitedPage = page;
+      }
+      if (typeof ntp4.BookmarksPage != 'undefined' &&
+          page instanceof ntp4.BookmarksPage) {
+        this.bookmarksPage = page;
+      }
+
+      // If we're appending an AppsPage and it's a temporary page, animate it.
+      var animate = page instanceof ntp4.AppsPage &&
+                    page.classList.contains('temporary');
+      // Make a deep copy of the dot template to add a new one.
+      var newDot = new ntp4.NavDot(page, title, titleIsEditable, animate);
+      page.navigationDot = newDot;
+      this.dotList.insertBefore(newDot, opt_refNode ? opt_refNode.navigationDot
+                                                    : null);
+      // Set a tab index on the first dot.
+      if (this.dotList.dots.length == 1)
+        newDot.tabIndex = 3;
+
+      this.eventTracker.add(page, 'pagelayout', this.onPageLayout_.bind(this));
+    },
+
+    /**
+     * Callback invoked by chrome with the apps available.
+     *
+     * Note that calls to this function can occur at any time, not just in
+     * response to a getApps request. For example, when a user
+     * installs/uninstalls an app on another synchronized devices.
+     * @param {Object} data An object with all the data on available
+     *        applications.
+     */
+    getAppsCallback: function(data) {
+      var startTime = Date.now();
+
+      // Clear any existing apps pages and dots.
+      // TODO(rbyers): It might be nice to preserve animation of dots after an
+      // uninstall. Could we re-use the existing page and dot elements?  It
+      // seems unfortunate to have Chrome send us the entire apps list after an
+      // uninstall.
+      while (this.appsPages.length > 0) {
+        var page = this.appsPages[0];
+        var dot = page.navigationDot;
+
+        this.eventTracker.remove(page);
+        page.tearDown();
+        page.parentNode.removeChild(page);
+        dot.parentNode.removeChild(dot);
+      }
+
+      // Get the array of apps and add any special synthesized entries
+      var apps = data.apps;
+
+      // Get a list of page names
+      var pageNames = data.appPageNames;
+
+      function stringListIsEmpty(list) {
+        for (var i = 0; i < list.length; i++) {
+          if (list[i])
+            return false;
+        }
+        return true;
+      }
+
+      // Sort by launch index
+      apps.sort(function(a, b) {
+        return a.app_launch_index - b.app_launch_index;
+      });
+
+      // An app to animate (in case it was just installed).
+      var highlightApp;
+
+      // Add the apps, creating pages as necessary
+      for (var i = 0; i < apps.length; i++) {
+        var app = apps[i];
+        var pageIndex = (app.page_index || 0);
+        while (pageIndex >= this.appsPages.length) {
+          var pageName = localStrings.getString('appDefaultPageName');
+          if (this.appsPages.length < pageNames.length)
+            pageName = pageNames[this.appsPages.length];
+
+          var origPageCount = this.appsPages.length;
+          this.appendTilePage(new ntp4.AppsPage(), pageName, true);
+          // Confirm that appsPages is a live object, updated when a new page is
+          // added (otherwise we'd have an infinite loop)
+          assert(this.appsPages.length == origPageCount + 1,
+                 'expected new page');
+        }
+
+        if (app.id == this.highlightAppId)
+          highlightApp = app;
+        else
+          this.appsPages[pageIndex].appendApp(app);
+      }
+
+      ntp4.AppsPage.setPromo(data.showPromo ? data : null);
+
+      // Tell the slider about the pages.
+      this.updateSliderCards();
+
+      if (highlightApp)
+        this.appAdded(highlightApp, true);
+
+      // Mark the current page.
+      this.cardSlider.currentCardValue.navigationDot.classList.add('selected');
+      logEvent('apps.layout: ' + (Date.now() - startTime));
+
+      document.documentElement.classList.remove('starting-up');
+    },
+
+    /**
+     * Called by chrome when a new app has been added to chrome or has been
+     * enabled if previously disabled.
+     * @param {Object} appData A data structure full of relevant information for
+     *     the app.
+     */
+    appAdded: function(appData, opt_highlight) {
+      if (appData.id == this.highlightAppId) {
+        opt_highlight = true;
+        this.highlightAppId = null;
+      }
+
+      var pageIndex = appData.page_index || 0;
+
+      if (pageIndex >= this.appsPages.length) {
+        while (pageIndex >= this.appsPages.length) {
+          this.appendTilePage(new ntp4.AppsPage(),
+                              localStrings.getString('appDefaultPageName'),
+                              true);
+        }
+        this.updateSliderCards();
+      }
+
+      var page = this.appsPages[pageIndex];
+      var app = $(appData.id);
+      if (app)
+        app.replaceAppData(appData);
+      else
+        page.appendApp(appData, opt_highlight);
+    },
+
+    /**
+     * Callback invoked by chrome whenever an app preference changes.
+     * @param {Object} data An object with all the data on available
+     *     applications.
+     */
+    appsPrefChangeCallback: function(data) {
+      for (var i = 0; i < data.apps.length; ++i) {
+        $(data.apps[i].id).appData = data.apps[i];
+      }
+
+      // Set the App dot names. Skip the first and last dots (Most Visited and
+      // Bookmarks).
+      var dots = this.dotList.getElementsByClassName('dot');
+      // TODO(csilv): Remove this calcluation if/when we remove the flag for
+      // for the bookmarks page.
+      var start = this.mostVisitedPage ? 1 : 0;
+      var length = this.bookmarksPage ? dots.length - 1 : dots.length;
+      for (var i = start; i < length; ++i) {
+        dots[i].displayTitle = data.appPageNames[i - start] || '';
+      }
+    },
+
+    /**
+     * Invoked whenever the pages in apps-page-list have changed so that
+     * the Slider knows about the new elements.
+     */
+    updateSliderCards: function() {
+      var pageNo = Math.min(this.cardSlider.currentCard,
+                            this.tilePages.length - 1);
+      this.cardSlider.setCards(Array.prototype.slice.call(this.tilePages),
+                                                          pageNo);
+      switch (this.shownPage) {
+        case templateData['apps_page_id']:
+          this.cardSlider.selectCardByValue(
+              this.appsPages[Math.min(this.shownPageIndex,
+                                      this.appsPages.length - 1)]);
+          break;
+        case templateData['bookmarks_page_id']:
+          if (this.bookmarksPage)
+            this.cardSlider.selectCardByValue(this.bookmarksPage);
+          break;
+        case templateData['most_visited_page_id']:
+          if (this.mostVisitedPage)
+            this.cardSlider.selectCardByValue(this.mostVisitedPage);
+          break;
+      }
+    },
+
+    /**
+     * Called whenever tiles should be re-arranging themselves out of the way
+     * of a moving or insert tile.
+     */
+    enterRearrangeMode: function() {
+      var tempPage = new ntp4.AppsPage();
+      tempPage.classList.add('temporary');
+      this.appendTilePage(tempPage,
+                          localStrings.getString('appDefaultPageName'),
+                          true);
+      var tempIndex = Array.prototype.indexOf.call(this.tilePages, tempPage);
+      if (this.cardSlider.currentCard >= tempIndex)
+        this.cardSlider.currentCard += 1;
+      this.updateSliderCards();
+
+      if (ntp4.getCurrentlyDraggingTile().firstChild.canBeRemoved())
+        $('footer').classList.add('showing-trash-mode');
+    },
+
+    /**
+     * Invoked whenever some app is released
+     * @param {Grabber.Event} e The Grabber RELEASE event.
+     */
+    leaveRearrangeMode: function(e) {
+      var tempPage = document.querySelector('.tile-page.temporary');
+      var dot = tempPage.navigationDot;
+      if (!tempPage.tileCount && tempPage != this.cardSlider.currentCardValue) {
+        dot.animateRemove();
+        var tempIndex = Array.prototype.indexOf.call(this.tilePages, tempPage);
+        if (this.cardSlider.currentCard > tempIndex)
+          this.cardSlider.currentCard -= 1;
+        tempPage.parentNode.removeChild(tempPage);
+        this.updateSliderCards();
+      } else {
+        tempPage.classList.remove('temporary');
+        this.saveAppPageName(tempPage,
+                             localStrings.getString('appDefaultPageName'));
+      }
+
+      $('footer').classList.remove('showing-trash-mode');
+    },
+
+    /**
+     * Callback for the 'pagelayout' event.
+     * @param {Event} e The event.
+     */
+    onPageLayout_: function(e) {
+      if (Array.prototype.indexOf.call(this.tilePages, e.currentTarget) !=
+          this.cardSlider.currentCard) {
+        return;
+      }
+
+      this.updatePageSwitchers();
+    },
+
+    /**
+     * Adjusts the size and position of the page switchers according to the
+     * layout of the current card.
+     */
+    updatePageSwitchers: function() {
+      if (!this.pageSwitcherStart || !this.pageSwitcherEnd)
+        return;
+
+      var page = this.cardSlider.currentCardValue;
+
+      this.pageSwitcherStart.hidden = !page ||
+          (this.cardSlider.currentCard == 0);
+      this.pageSwitcherEnd.hidden = !page ||
+          (this.cardSlider.currentCard == this.cardSlider.cardCount - 1);
+
+      if (!page)
+        return;
+
+      var pageSwitcherLeft = isRTL() ? this.pageSwitcherEnd
+                                     : this.pageSwitcherStart;
+      var pageSwitcherRight = isRTL() ? this.pageSwitcherStart
+                                      : this.pageSwitcherEnd;
+      var scrollbarWidth = page.scrollbarWidth;
+      pageSwitcherLeft.style.width =
+          (page.sideMargin + 13) + 'px';
+      pageSwitcherLeft.style.left = '0';
+      pageSwitcherRight.style.width =
+          (page.sideMargin - scrollbarWidth + 13) + 'px';
+      pageSwitcherRight.style.right = scrollbarWidth + 'px';
+
+      var offsetTop = page.querySelector('.tile-page-content').offsetTop + 'px';
+      pageSwitcherLeft.style.top = offsetTop;
+      pageSwitcherRight.style.top = offsetTop;
+      pageSwitcherLeft.style.paddingBottom = offsetTop;
+      pageSwitcherRight.style.paddingBottom = offsetTop;
+    },
+
+    /**
+     * Returns the index of the given page.
+     * @param {AppsPage} page The AppsPage for we wish to find.
+     * @return {number} The index of |page|, or -1 if it is not here.
+     */
+    getAppsPageIndex: function(page) {
+      return Array.prototype.indexOf.call(this.appsPages, page);
+    },
+
+    /**
+     * Handler for CARD_CHANGED on cardSlider.
+     * @param {Event} e The CARD_CHANGED event.
+     */
+    cardChangedHandler: function(e) {
+      var page = e.cardSlider.currentCardValue;
+
+      // Don't change shownPage until startup is done (and page changes actually
+      // reflect user actions).
+      if (!document.documentElement.classList.contains('starting-up')) {
+        if (page.classList.contains('apps-page')) {
+          this.shownPage = templateData['apps_page_id'];
+          this.shownPageIndex = this.getAppsPageIndex(page);
+        } else if (page.classList.contains('most-visited-page')) {
+          this.shownPage = templateData['most_visited_page_id'];
+          this.shownPageIndex = 0;
+        } else if (page.classList.contains('bookmarks-page')) {
+          this.shownPage = templateData['bookmarks_page_id'];
+          this.shownPageIndex = 0;
+        } else {
+          console.error('unknown page selected');
+        }
+        chrome.send('pageSelected', [this.shownPage, this.shownPageIndex]);
+      }
+
+      // Update the active dot
+      var curDot = this.dotList.getElementsByClassName('selected')[0];
+      if (curDot)
+        curDot.classList.remove('selected');
+      page.navigationDot.classList.add('selected');
+      this.updatePageSwitchers();
+    },
+
+    /*
+     * Save the name of an app page.
+     * Store the app page name into the preferences store.
+     * @param {AppsPage} appPage The app page for which we wish to save.
+     * @param {string} name The name of the page.
+     */
+    saveAppPageName: function(appPage, name) {
+      var index = this.getAppsPageIndex(appPage);
+      assert(index != -1);
+      chrome.send('saveAppPageName', [name, index]);
+    },
+
+    /**
+     * Window resize handler.
+     * @private
+     */
+    onWindowResize_: function(e) {
+      this.cardSlider.resize(this.sliderFrame.offsetWidth);
+      this.updatePageSwitchers();
+    },
+
+    /**
+     * Handler for key events on the page. Ctrl-Arrow will switch the visible
+     * page.
+     * @param {Event} e The KeyboardEvent.
+     */
+    onDocKeyDown: function(e) {
+      if (!e.ctrlKey || e.altKey || e.metaKey || e.shiftKey)
+        return;
+
+      var direction = 0;
+      if (e.keyIdentifier == 'Left')
+        direction = -1;
+      else if (e.keyIdentifier == 'Right')
+        direction = 1;
+      else
+        return;
+
+      var cardIndex =
+          (this.cardSlider.currentCard + direction +
+           this.cardSlider.cardCount) % this.cardSlider.cardCount;
+      this.cardSlider.selectCard(cardIndex, true);
+
+      e.stopPropagation();
+    }
+  };
+
+  /**
+   * Simple common assertion API
+   * @param {*} condition The condition to test.  Note that this may be used to
+   *     test whether a value is defined or not, and we don't want to force a
+   *     cast to Boolean.
+   * @param {string=} opt_message A message to use in any error.
+   */
+  function assert(condition, opt_message) {

[Evan Stade, 2011/11/07 23:59:20]

some of these functions should go in util.js

[xiyuan, 2011/11/08 21:09:18]

Done. Moved assert, getRequiredEleemnt and isRTL into util.js

+    'use strict';
+    if (!condition) {
+      var msg = 'Assertion failed';
+      if (opt_message)
+        msg = msg + ': ' + opt_message;
+      throw new Error(msg);
+    }
+  }
+
+  /**
+   * Get an element that's known to exist by its ID. We use this instead of just
+   * calling getElementById and not checking the result because this lets us
+   * satisfy the JSCompiler type system.
+   * @param {string} id The identifier name.
+   * @return {!Element} the Element.
+   */
+  function getRequiredElement(id) {
+    var element = document.getElementById(id);
+    assert(element, 'Missing required element: ' + id);
+    return element;
+  }
+
+  /**
+   * Wrapper to forward the callback to corresponding PageListView member.
+   */
+  function getAppsCallback(data) {
+    instance.getAppsCallback(data);
+  }
+
+  /**
+   * Wrapper to forward the callback to corresponding PageListView member.
+   */
+  function appAdded(appData, opt_highlight) {
+    instance.appAdded(appData, opt_highlight);
+  }
+
+  /**
+   * Sets that an app should be highlighted if it is added. Called right before
+   * appAdded for new installs.
+   */
+  function setAppToBeHighlighted(appId) {
+    instance.highlightAppId = appId;
+  }
+
+  /**
+   * Called by chrome when an existing app has been disabled or
+   * removed/uninstalled from chrome.
+   * @param {Object} appData A data structure full of relevant information for
+   *     the app.
+   * @param {boolean} isUninstall True if the app is being uninstalled;
+   *     false if the app is being disabled.
+   */
+  function appRemoved(appData, isUninstall) {
+    var app = $(appData.id);
+    assert(app, 'trying to remove an app that doesn\'t exist');
+
+    if (!isUninstall)
+      app.replaceAppData(appData);
+    else
+      app.remove();
+  }
+
+  /**
+   * Wrapper to forward the callback to corresponding PageListView member.
+   */
+  function appsPrefChangeCallback(data) {
+    instance.appsPrefChangedCallback(data);
+  }
+
+  /**
+   * Listener for offline status change events. Updates apps that are
+   * not offline-enabled to be grayscale if the browser is offline.
+   */
+  function updateOfflineEnabledApps() {
+    var apps = document.querySelectorAll('.app');
+    for (var i = 0; i < apps.length; ++i) {
+      if (apps[i].appData.enabled && !apps[i].appData.offline_enabled) {
+        apps[i].setIcon();
+        apps[i].loadIcon();
+      }
+    }
+  }
+
+  function getCardSlider() {
+    return instance.cardSlider;
+  }
+
+  /**
+   * Wrapper to forward the callback to corresponding PageListView member.
+   */
+  function enterRearrangeMode() {
+    instance.enterRearrangeMode();
+  }
+
+  /**
+   * Wrapper to forward the callback to corresponding PageListView member.
+   */
+  function leaveRearrangeMode(e) {
+    instance.leaveRearrangeMode(e);
+  }
+
+  /**
+   * Check the directionality of the page.
+   * @return {boolean} True if Chrome is running an RTL UI.
+   */
+  function isRTL() {
+    return document.documentElement.dir == 'rtl';
+  }
+
+  /**
+   * Wrapper to forward the callback to corresponding PageListView member.
+   */
+  function getAppsPageIndex(page) {
+    instance.getAppsPageIndex(page);
+  }
+
+  /**
+   * Wrapper to forward the callback to corresponding PageListView member.
+   */
+  function saveAppPageName(appPage, name) {
+    instance.saveAppPageName(appPage, name);
+  }
+
+  return {
+    appAdded: appAdded,
+    appendTilePage: appendTilePage,
+    appRemoved: appRemoved,
+    appsPrefChangeCallback: appsPrefChangeCallback,
+    assert: assert,
+    enterRearrangeMode: enterRearrangeMode,
+    getAppsCallback: getAppsCallback,
+    getAppsPageIndex: getAppsPageIndex,
+    getCardSlider: getCardSlider,
+    getRequiredElement: getRequiredElement,
+    isRTL: isRTL,
+    leaveRearrangeMode: leaveRearrangeMode,
+    saveAppPageName: saveAppPageName,
+    setAppToBeHighlighted: setAppToBeHighlighted,
+    updateOfflineEnabledApps: updateOfflineEnabledApps,
+    PageListView: PageListView
+  };
+});
+
+var appendTilePage = ntp4.appendTilePage;

[Evan Stade, 2011/11/07 23:59:20]

are you planning to use all of this in the aura homepage? If not, this should
all be in new_tab.js.

This file needs to be moved to resources/shared/... and the namespace changed to
cr.ui. (card_slider.js and possibly other files will have to move as well)

[xiyuan, 2011/11/08 21:09:18]

I only need appsPrefChangeCallback and getAppsCallback that are used by
app_launcher_handler. I moved those back into new_tab.js and added cooresponding
part in app_list.js.

However, we probably should not move this file into shared because it's very
application specific and depends on your DOM tree.

card_slider.js etc should be moved into shared but not sure if I should do that
in this CL though. I might not be the best guy to do the move especially the
touch handling part.

+var appsPrefChangeCallback = ntp4.appsPrefChangeCallback;
+var assert = ntp4.assert;
+var getAppsCallback = ntp4.getAppsCallback;
+var getRequiredElement = ntp4.getRequiredElement;
+
+window.addEventListener('online', ntp4.updateOfflineEnabledApps);
+window.addEventListener('offline', ntp4.updateOfflineEnabledApps);