local ntp: fix up accessibility tree

chrome/browser/resources/local_ntp/most_visited_single.js

 /* Copyright 2015 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. */
 
  // Single iframe for NTP tiles.
 (function() {
 'use strict';
 
 
 /**
@@ skipping 361 matching lines @@
   var position = tiles.children.length;
   logMostVisitedImpression(position, data.tileSource);
 
   tile.className = 'mv-tile';
   tile.setAttribute('data-tid', data.tid);
   var html = [];
   if (!USE_ICONS) {
     html.push('<div class="mv-favicon"></div>');
   }
   html.push('<div class="mv-title"></div><div class="mv-thumb"></div>');
-  html.push('<div class="mv-x"></div>');
+  html.push('<div class="mv-x" role="button"></div>');
   tile.innerHTML = html.join('');
   tile.lastElementChild.title = queryArgs['removeTooltip'] || '';
 
   if (isSchemeAllowed(data.url)) {
     tile.href = data.url;
   }
+  tile.setAttribute('aria-label', data.title);
   tile.title = data.title;
   if (data.impressionUrl) {
     impressionUrl = data.impressionUrl;
   }
   if (data.pingUrl) {
     tile.addEventListener('click', function(ev) {
       navigator.sendBeacon(data.pingUrl);
     });
   }
 
@@ skipping 211 matching lines @@
     var html = document.querySelector('html');
     html.dir = 'rtl';
   }
 
   window.addEventListener('message', handlePostMessage);
 };
 
 
 window.addEventListener('DOMContentLoaded', init);
 })();