[NTP4] Auto-deletion of empty apps panes.

chrome/browser/resources/ntp4/page_list_view.js

Index: chrome/browser/resources/ntp4/page_list_view.js
diff --git a/chrome/browser/resources/ntp4/page_list_view.js b/chrome/browser/resources/ntp4/page_list_view.js
index a5065b12ff35217dad3cde04fba1ee714c689a1f..6749145652abd875ad7eb06ba729bb7ef652f910 100644
--- a/chrome/browser/resources/ntp4/page_list_view.js
+++ b/chrome/browser/resources/ntp4/page_list_view.js
@@ -29,34 +29,36 @@ cr.define('ntp4', function() {
 
   PageListView.prototype = {
     /**
-     * The CardSlider object to use for changing app pages.
-     * @type {CardSlider|undefined}
+     * A list of all 'apps-page' elements.
+     * @type {!NodeList|undefined}
      */
-    cardSlider: undefined,
+    appsPages: undefined,
 
     /**
-     * The frame div for cardSlider.
-     * @type {!Element|undefined}
+     * The CardSlider object to use for changing app pages.
+     * @type {CardSlider|undefined}
      */
-    sliderFrame: undefined,
+    cardSlider: undefined,
 
     /**
-     * The 'page-list' element.
+     * The 'dots-list' element.
      * @type {!Element|undefined}
      */
-    pageList: undefined,
+    dotList: undefined,
 
     /**
-     * A list of all 'tile-page' elements.
-     * @type {!NodeList|undefined}
+     * EventTracker for managing event listeners for page events.
+     * @type {!EventTracker}
      */
-    tilePages: undefined,
+    eventTracker: new EventTracker,
 
     /**
-     * A list of all 'apps-page' elements.
-     * @type {!NodeList|undefined}
+     * 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}
      */
-    appsPages: undefined,
+    highlightAppId: null,
 
     /**
      * The Most Visited page.
@@ -65,10 +67,10 @@ cr.define('ntp4', function() {
     mostVisitedPage: undefined,
 
     /**
-     * The 'dots-list' element.
+     * The 'page-list' element.
      * @type {!Element|undefined}
      */
-    dotList: undefined,
+    pageList: undefined,
 
     /**
      * The left and right paging buttons.
@@ -78,14 +80,6 @@ cr.define('ntp4', function() {
     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}
      */
@@ -99,18 +93,24 @@ cr.define('ntp4', function() {
     shownPageIndex: 0,
 
     /**
-     * EventTracker for managing event listeners for page events.
-     * @type {!EventTracker}
+     * The frame div for this.cardSlider.
+     * @type {!Element|undefined}
      */
-    eventTracker: new EventTracker,
+    sliderFrame: undefined,
 
     /**
-     * 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}
+     * A list of all 'tile-page' elements.
+     * @type {!NodeList|undefined}
      */
-    highlightAppId: null,
+    tilePages: 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,
 
     /**
      * Initializes page list view.
@@ -183,13 +183,104 @@ cr.define('ntp4', function() {
     },
 
     /**
+     * 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;
+      this.ensureAppsPageAtIndex_(pageIndex);
+
+      var page = this.appsPages[pageIndex];
+      var app = $(appData.id);
+      if (app)
+        app.replaceAppData(appData);
+      else
+        page.appendApp(appData, opt_highlight);
+    },
+
+    /**
+     * 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.
+     */
+    appRemoved: function(appData, isUninstall, fromPage) {
+      var app = $(appData.id);
+      assert(app, 'trying to remove an app that doesn\'t exist');
+
+      if (!isUninstall) {
+        app.replaceAppData(appData);
+      } else {
+        // Unset the ID immediately, because the app is already gone. But leave
+        // the tile on the page as it animates out.
+        app.id = '';
+        // If the uninstall was from this page, run the blipout animation and
+        // remove the tile in the webkitAnimationEnd handler in apps_page.js.
+        // Otherwise delete the tile without auto-deleting the page to avoid
+        // re-deleting the same page (or the page that slid in to take its
+        // place).
+        if (fromPage) {
+          app.classList.add('removing-tile-contents');
+        } else {
+          var tilePage = app.tile.tilePage;
+          app.tile.remove(false, true);
+          this.removeAppsPageIfEmpty(tilePage, false, true);
+        }
+      }
+    },
+
+    /**
+     * Re-order apps on this invactive page when an active NTP gets re-ordered.
+     * @param {Object} data Position hashmap ordered by app id with indices:
+     *    {id => {page_index: ##, app_launch_index: ##}}
+     */
+    appsReordered: function(data) {
+      var pages = Object.keys(data);
+      for (var i = 0; i < pages.length; ++i) {
+        var page = data[pages[i]];
+        var indices = Object.keys(page);
+        for (var j = 0; j < indices.length; ++j) {
+          var app = $(page[indices[j]]);
+          if (i != this.getAppsPageIndex(app.tile.tilePage) ||
+              j != app.tile.index) {
+            var tile = app.tile.remove(false, true);
+            this.ensureAppsPageAtIndex_(i);
+            var appsPage = this.appsPages[i];
+            appsPage.addTileAt(tile.firstChild, j);
+            if (appsPage.classList.contains('selected-card'))
+              app.loadIcon();
+          }
+        }
+      }
+      for (var i = 0; i < this.appsPages.length; ++i) {
+        // If a page is now empty, remove it and move backward one in our
+        // array-like object as it is a live NodeList and the length/indice
+        // change when you update it. Otherwise, reuse cleanupDrag() to
+        // re-position the tiles like when a user is done dragging.
+        if (this.removeAppsPageIfEmpty(this.appsPages[i], false, true))
+          --i;
+        else
+          this.appsPages[i].cleanupDrag();
+      }
+    },
+
+    /**
      * Appends a tile page.
      *
      * @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

[Evan Stade, 2011/12/02 00:53:24]

never end your sentences in a preposition. This should read "Optional reference
node of front in which to insert".

I kid.

[Dan Beam, 2011/12/02 01:25:11]

I read this part too late, damn it, lol.

"I need to read faster!" - Mitch Hedberg

-     * of.
+     *     of.
      * When opt_refNode is falsey, |page| will just be appended to the end of
      * the page list.
      */
@@ -197,6 +288,21 @@ cr.define('ntp4', function() {
       // When opt_refNode is falsey, insertBefore acts just like appendChild.
       this.pageList.insertBefore(page, opt_refNode);
 
+      if (!document.documentElement.classList.contains('starting-up')) {
+        // If we're inserting a card in front of the current card, add 1 to the
+        // current index to adjust for the new card in the order.
+        var index = Array.prototype.indexOf.call(this.tilePages, page);
+        if (typeof this.cardSlider.currentCard != 'undefined' &&
+            index <= this.cardSlider.currentCard) {
+          this.cardSlider.currentCard += 1;
+        }
+        if (page instanceof ntp4.AppsPage &&
+            this.shownPage == templateData['apps_page_id'] &&
+            this.getAppsPageIndex(page) <= this.shownPageIndex) {
+          this.shownPageIndex += 1;
+        }
+      }
+
       // Remember special MostVisitedPage.
       if (typeof ntp4.MostVisitedPage != 'undefined' &&
           page instanceof ntp4.MostVisitedPage) {
@@ -221,21 +327,90 @@ cr.define('ntp4', function() {
     },
 
     /**
-     * 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.
+     * Callback invoked by chrome whenever an app preference changes.
+     * @param {Object} data An object with all the data on available
+     *     applications.
      */
-    appRemoved: function(appData, isUninstall) {
-      var app = $(appData.id);
-      assert(app, 'trying to remove an app that doesn\'t exist');
+    appsPrefChangedCallback: function(data) {
+      for (var i = 0; i < data.apps.length; ++i) {
+        var el = $(data.apps[i].id);
+        // There won't be an element when the temporary page is first saved on a
+        // drop on a new apps page.
+        if (el)
+          el.appData = data.apps[i];
+      }
 
-      if (!isUninstall)
-        app.replaceAppData(appData);
-      else
-        app.remove();
+      // Set the App dot names. Skip dots that don't belong to apps pages.
+      var dots = this.dotList.getElementsByClassName('dot');
+      var firstAppDot = this.getTilePageIndex(this.appsPages[0]);
+      for (var i = 0; i < this.appsPages.length; ++i) {
+        dots[firstAppDot + i].displayTitle = data.appsPageNames[i] || '';
+      }
+    },
+
+    /**
+     * Handler for CARD_CHANGED on cardSlider.
+     * @param {Event} e The CARD_CHANGED event.
+     * @private
+     */
+    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')) {
+        var prevPage = this.shownPage;
+        var prevIndex = this.shownPageIndex;
+        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 {
+          console.error('unknown page selected');
+        }
+        if (prevPage != this.shownPage || prevIndex != this.shownPageIndex)
+          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();
+    },
+
+    /**
+     * Ensure there is an apps page at the given |index|. If index is smaller
+     * than the current number of apps pages, additional apps pages will be
+     * created.
+     * @param {number} index An apps page index to ensure exists.
+     */
+    ensureAppsPageAtIndex_: function(index) {
+      if (index >= this.appsPages.length) {
+        var pageName = localStrings.getString('appDefaultPageName');
+        while (index >= this.appsPages.length)
+          this.appendTilePage(new ntp4.AppsPage(), pageName, true);
+        this.updateSliderCards();
+      }
+    },
+
+    /**
+     * 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');
+      var pageName = localStrings.getString('appDefaultPageName');
+      this.appendTilePage(tempPage, pageName, true);
+      this.updateSliderCards();
+      this.updatePageSwitchers();
+
+      if (ntp4.getCurrentlyDraggingTile().firstChild.canBeRemoved())
+        $('footer').classList.add('showing-trash-mode');
     },
 
     /**
@@ -257,19 +432,16 @@ cr.define('ntp4', function() {
       // 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);
+        this.removeTilePage(page);
       }
 
       // 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;
+      var pageNames = data.appsPageNames;
 
       function stringListIsEmpty(list) {
         for (var i = 0; i < list.length; i++) {
@@ -326,115 +498,84 @@ cr.define('ntp4', function() {
     },
 
     /**
-     * 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.
+     * Returns the index of the given apps page.
+     * @param {AppsPage} page The AppsPage we wish to find.
+     * @return {number} The index of |page| or -1 if it is not in the
+     *    collection.
      */
-    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);
+    getAppsPageIndex: function(page) {
+      return Array.prototype.indexOf.call(this.appsPages, page);
     },
 
     /**
-     * Callback invoked by chrome whenever an app preference changes.
-     * @param {Object} data An object with all the data on available
-     *     applications.
+     * Returns the index of a given tile page.
+     * @param {TilePage} page The TilePage we wish to find.
+     * @return {number} The index of |page| or -1 if it is not in the
+     *    collection.
      */
-    appsPrefChangedCallback: 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 dot (Most Visited).
-      var dots = this.dotList.getElementsByClassName('dot');
-      var start = this.mostVisitedPage ? 1 : 0;
-      for (var i = start; i < dots.length; ++i) {
-        dots[i].displayTitle = data.appPageNames[i - start] || '';
-      }
+    getTilePageIndex: function(page) {
+      return Array.prototype.indexOf.call(this.tilePages, page);
     },
 
     /**
-     * Invoked whenever the pages in apps-page-list have changed so that
-     * the Slider knows about the new elements.
+     * Invoked whenever some app is released
      */
-    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['most_visited_page_id']:
-          if (this.mostVisitedPage)
-            this.cardSlider.selectCardByValue(this.mostVisitedPage);
-          break;
+    leaveRearrangeMode: function() {
+      var tempPage = document.querySelector('.tile-page.temporary');
+      // If there's a temp page and it wasn't removed for being empty.
+      if (tempPage && !this.removeAppsPageIfEmpty(tempPage, true)) {
+        this.saveAppsPageName(tempPage, tempPage.navigationDot.displayTitle);
+        tempPage.classList.remove('temporary');
       }
+
+      $('footer').classList.remove('showing-trash-mode');
     },
 
     /**
-     * Called whenever tiles should be re-arranging themselves out of the way
-     * of a moving or insert tile.
+     * Move to a non-empty page before/while we delete an empty one.
+     * @param {Element} appsPage An empty apps page that we want to move off of
+     *     (probably because it's empty).
+     * @param {=boolean} animate Whether we should animate or not.
+     * @param {=function} callback A callback to be executed when the move is
+     *     done.
      */
-    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');
+    moveOffEmptyAppsPage: function(appsPage, opt_animate, opt_callback) {
+      assert(appsPage instanceof ntp4.AppsPage,
+             '|appsPage| is really an AppsPage');
+      // Select the page further toward the end than the empty |appsPage|. If
+      // the empty |appsPage| is at the end, the apps page before it will be
+      // selected.
+      var index = this.getAppsPageIndex(appsPage);
+      assert(index >= 0, '|appsPage| is in this.appsPages');
+      var direction = (index == this.appsPages.length - 1 ? -1 : 1);
+      this.cardSlider.selectCard(this.cardSlider.currentCard + direction,
+                                 opt_animate, opt_callback);
     },
 
     /**
-     * Invoked whenever some app is released
+     * Handler for key events on the page. Ctrl-Arrow will switch the visible
+     * page.
+     * @param {Event} e The KeyboardEvent.
+     * @private
      */
-    leaveRearrangeMode: function() {
-      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'));
-      }
+    onDocKeyDown_: function(e) {
+      if (!e.ctrlKey || e.altKey || e.metaKey || e.shiftKey)
+        return;
 
-      $('footer').classList.remove('showing-trash-mode');
+      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();
     },
 
     /**
@@ -451,6 +592,84 @@ cr.define('ntp4', function() {
     },
 
     /**
+     * Window resize handler.
+     * @private
+     */
+    onWindowResize_: function(e) {
+      this.cardSlider.resize(this.sliderFrame.offsetWidth);
+      this.updatePageSwitchers();
+    },
+
+    /**
+     * Utility function to remove both a tile page and corresponding nav dot.
+     * NOTE: If |animated| is true, this function will return before the
+     * animation is finished.
+     * @param {Element} appsPage An apps page to be removed if it has no tiles.
+     * @param {=boolean} opt_animate An optional param to animate the removal.
+     * @param {=boolean} opt_dontSave Whether we should notify other NTPs this
+     *     page was deleted (defaults to yes).
+     * @returns {boolean} If the page was removed.
+     */
+    removeAppsPageIfEmpty: function(appsPage, opt_animate, opt_dontSave) {
+      if (appsPage && appsPage.tileCount === 0) {
+        var whenDone = function() {
+          if (!opt_dontSave) {
+            chrome.send('deleteAppsPage',
+                [this.getAppsPageIndex(appsPage),
+                 appsPage.classList.contains('temporary')]);
+          }
+          this.removeTilePage(appsPage, opt_animate);
+          this.updateSliderCards();
+          this.updatePageSwitchers();
+        };
+        if (appsPage == this.cardSlider.currentCardValue)
+          this.moveOffEmptyAppsPage(appsPage, opt_animate, whenDone.bind(this));
+        else
+          whenDone.call(this);
+        return true;
+      }
+      return false;
+    },
+
+    /**
+     * Removes a page and navigation dot (if the navdot exists).
+     * @param {Element} page The page to be removed.
+     * @param {boolean} animate If the removal should be animated.
+     */
+    removeTilePage: function(page, animate) {
+      if (!document.documentElement.classList.contains('starting-up')) {
+        // If the card being deleted is before the current card, keep the same
+        // spot in the list by removing 1 from the current card index.
+        var index = Array.prototype.indexOf.call(this.tilePages, page);
+        if (index < this.cardSlider.currentCard) {
+          this.cardSlider.currentCard -= 1;
+        }
+        // If the page we're about to delete is in front of the current page,
+        // remove 1 from the shown page index.
+        if (page instanceof ntp4.AppsPage &&
+            this.shownPage == templateData['apps_page_id'] &&
+            this.getAppsPageIndex(page) < this.shownPageIndex) {
+          this.shownPageIndex -= 1;
+        }
+      }
+      if (page.navigationDot)
+        page.navigationDot.remove(animate);
+      page.remove();
+    },
+
+    /*
+     * Save the name of an app page.
+     * Store the app page name into the preferences store.
+     * @param {AppsPage} appsPage The app page for which we wish to save.
+     * @param {string} name The name of the page.
+     */
+    saveAppsPageName: function(appsPage, name) {
+      var index = this.getAppsPageIndex(appsPage);
+      assert(index != -1);
+      chrome.send('saveAppsPageName', [name, index]);
+    },
+
+    /**
      * Adjusts the size and position of the page switchers according to the
      * layout of the current card.
      */
@@ -488,64 +707,40 @@ cr.define('ntp4', function() {
     },
 
     /**
-     * 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.
-     * @private
+     * Invoked whenever the pages in apps-page-list have changed so that
+     * the Slider knows about the new elements.
      */
-    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 {
-          console.error('unknown page selected');
-        }
-        chrome.send('pageSelected', [this.shownPage, this.shownPageIndex]);
+    updateSliderCards: function() {
+      var index = -1;
+      var prevPage = this.shownPage;
+      var prevIndex = this.shownPageIndex;
+      var tiles = Array.prototype.slice.call(this.tilePages);
+      // It doesn't hurt to clamp value this every time, even if it's only
+      // applicable to apps. It helps self-heal strange / un-expected data, i.e.
+      // going from an apps page to the most visited page directly without
+      // setting this.shownPageIndex = 0 somehow.
+      this.shownPageIndex = Math.max(0, Math.min(this.shownPageIndex,
+                                                 this.appsPages.length - 1));
+      switch (this.shownPage) {
+        case templateData['apps_page_id']:
+          index = tiles.indexOf(this.appsPages[this.shownPageIndex]);
+          break;
+        case templateData['most_visited_page_id']:
+          index = tiles.indexOf(this.mostVisitedPage);
+          break;
       }
-
-      // 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();
+      // If shownPage was saved as a page that's now disabled or the shownPage
+      // doesn't exist any more, index will be -1. Change to the preferred
+      // default page (first apps pane) in this case.
+      if (index < 0) {
+        this.shownPage = templateData['apps_page_id'];
+        index = tiles.indexOf(this.appsPages[0]);
+      }
+      // Set the new cards and index.
+      this.cardSlider.setCards(tiles, index);
+      // If we got new page or index, update the pref.
+      if (prevIndex != this.shownPageIndex || prevPage != this.shownPage)
+        chrome.send('pageSelected', [this.shownPage, this.shownPageIndex]);
     },
 
     /**
@@ -562,32 +757,6 @@ cr.define('ntp4', function() {
         }
       }
     },
-
-    /**
-     * Handler for key events on the page. Ctrl-Arrow will switch the visible
-     * page.
-     * @param {Event} e The KeyboardEvent.
-     * @private
-     */
-    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();
-    }
   };
 
   return {