Fix accessibility issues on most visited page for android's NTP.

chrome/browser/resources/ntp_android/ntp_android.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.
 
 // File Description:
 //     Contains all the necessary functions for rendering the NTP on mobile
 //     devices.
 
 /**
  * The event type used to determine when a touch starts.
@@ skipping 307 matching lines @@
   var syncState = SyncState.INITIAL;
 
   /**
    * Whether or not sync is enabled. It will be undefined until
    * setSyncEnabled() is called.
    * @type {?boolean}
    */
   var syncEnabled = undefined;
 
   /**
+   * The current most visited data being displayed.
+   * @type {Array.<Object>}
+   */
+  var mostVisitedData_ = [];
+
+  /**
    * The current bookmark data being displayed. Keep a reference to this data
    * in case the sync enabled state changes.  In this case, the bookmark data
    * will need to be refiltered.
    * @type {?Object}
    */
   var bookmarkData;
 
   /**
    * Keep track of any outstanding timers related to updating the sync section.
    */
@@ skipping 310 matching lines @@
     };
     thumbnailImg.src = backgroundUrl;
 
     thumbnailContainer.appendChild(thumbnail);
     var innerBorder = createDiv('inner-border');
     thumbnailContainer.appendChild(innerBorder);
     thumbnailCell.appendChild(thumbnailContainer);
     var title = createDiv('title');
     title.textContent = item.title;
     var spacerImg = createElement('img', 'title-spacer');
+    spacerImg.alt = '';
     title.insertBefore(spacerImg, title.firstChild);
     thumbnailCell.appendChild(title);
 
-    wrapClickHandler(thumbnailContainer, item, opt_clickCallback);
+    wrapClickHandler(thumbnailCell, item, opt_clickCallback);
 
     thumbnailCell.setAttribute(CONTEXT_MENU_URL_KEY, item.url);
     thumbnailCell.contextMenuItem = item;
     return thumbnailCell;
   }
 
   /**
    * Creates a shortcut DOM element based on the item specified item
    * configuration using the favicon layout used for bookmarks.
    *
@@ skipping 231 matching lines @@
    */
   function setMostVisitedPages(data, hasBlacklistedUrls) {
     setNumberOfMostVisitedPages(data.length);
     // limit the number of most visited items to display
     if (isPhone() && data.length > 6) {
       data.splice(6, data.length - 6);
     } else if (isTablet() && data.length > 8) {
       data.splice(8, data.length - 8);
     }
 
+    if (equals(data, mostVisitedData_))
+      return;
+
     var clickFunction = function(item) {
       chrome.send('metricsHandler:recordAction', ['MobileNTPMostVisited']);
       window.location = item.url;
     };
     populateData(findList('most_visited'), SectionType.MOST_VISITED, data,
         makeMostVisitedItem, clickFunction);
     computeDynamicLayout();
+
+    mostVisitedData_ = data;
   }
 
   /**
    * Updates the recently closed tabs.
    *
    * @param {Array.<Object>} List of data for displaying the list of recently
    *     closed tabs (see C++ handler for model description).
    */
   function setRecentlyClosedTabs(data) {
     var container = $('recently_closed_container');
@@ skipping 1553 matching lines @@
     setSyncEnabled: setSyncEnabled,
     snapshots: snapshots
   };
 });
 
 /////////////////////////////////////////////////////////////////////////////
 //Utility Functions.
 /////////////////////////////////////////////////////////////////////////////
 
 /**
+ * A best effort approach for checking simple data object equality.
+ * @param {?} val1 The first value to check equality for.
+ * @param {?} val2 The second value to check equality for.
+ * @return {boolean} Whether the two objects are equal(ish).
+ */
+function equals(val1, val2) {
+  if (typeof val1 != 'object' || typeof val2 != 'object')
+    return val1 === val2;
+
+  // Object and array equality checks.
+  var keyCountVal1 = 0;
+  for (var key in val1) {
+    if (!(key in val2) || !equals(val1[key], val2[key]))
+      return false;
+    keyCountVal1++;
+  }
+  var keyCountVal2 = 0;
+  for (var key in val2)
+    keyCountVal2++;
+  if (keyCountVal1 != keyCountVal2)
+    return false;
+  return true;
+}
+
+/**
  * Alias for document.getElementById.
  * @param {string} id The ID of the element to find.
  * @return {HTMLElement} The found element or null if not found.
  */
 function $(id) {
   return document.getElementById(id);
 }
 
 /**
  * @return {boolean} Whether the device is currently in portrait mode.
@@ skipping 111 matching lines @@
 // NTP Entry point.
 /////////////////////////////////////////////////////////////////////////////
 
 /*
  * Handles initializing the UI when the page has finished loading.
  */
 window.addEventListener('DOMContentLoaded', function(evt) {
   ntp.init();
   $('content-area').style.display = 'block';
 });