[Local NTP] Add role="presentation" on the New Tab Page iframe.

chrome/browser/resources/local_ntp/local_ntp.js

 // Copyright 2013 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 The local InstantExtended NTP.
  */
 
 
@@ skipping 680 matching lines @@
 
   // Container of tile contents.
   var innerElem = createAndAppendElement(tileElem, 'div', CLASSES.TILE_INNER);
 
   // The iframe which renders the page title.
   var titleElem = document.createElement('iframe');
   // Enable tab navigation on the iframe, which will move the selection to the
   // link element (which also has a tabindex).
   titleElem.tabIndex = '0';
 
+  // Make the iframe invisible to screen readers.

[dmazzoni, 2015/01/29 18:48:44]

Let's reword this slightly. It implies that we're hiding the whole frame and its
contents. How about something like:

// Make the iframe presentational for accessibility so screen readers perceive
the iframe content as just part of the same page.

[Mathieu, 2015/01/29 18:53:35]

Done.

+  titleElem.setAttribute('role', 'presentation');
+
   // Why iframes have IDs:
   //
   // On navigating back to the NTP we see several onmostvisitedchange() events
   // in series with incrementing RIDs. After the first event, a set of iframes
   // begins loading RIDs n, n+1, ..., n+k-1; after the second event, these get
   // destroyed and a new set begins loading RIDs n+k, n+k+1, ..., n+2k-1.
   // Now due to crbug.com/68841, Chrome incorrectly loads the content for the
   // first set of iframes into the most recent set of iframes.
   //
   // Giving iframes distinct ids seems to cause some invalidation and prevent
@@ skipping 11 matching lines @@
   if (NTP_DESIGN.thumbnailFallback) {
     var fallbackElem = createAndAppendElement(
         innerElem, 'div', CLASSES.THUMBNAIL_FALLBACK);
     if (NTP_DESIGN.thumbnailFallback === THUMBNAIL_FALLBACK.DOT)
       createAndAppendElement(fallbackElem, 'div', CLASSES.DOT);
   }
 
   // The iframe which renders either a thumbnail or domain element.
   var thumbnailElem = document.createElement('iframe');
   thumbnailElem.tabIndex = '-1';
+  // Make the iframe invisible to screen readers.
   thumbnailElem.setAttribute('aria-hidden', 'true');
+  titleElem.setAttribute('role', 'presentation');

[dmazzoni, 2015/01/29 18:48:43]

This one is unnecessary, the iframe is already invisible to screen readers due
to aria-hidden

[Mathieu, 2015/01/29 18:53:35]

Done.

   // Keep this ID here. See comment above.
   thumbnailElem.id = 'thumb-' + rid;
   thumbnailElem.className = CLASSES.THUMBNAIL;
   thumbnailElem.src = getMostVisitedThumbnailIframeUrl(rid, position);
   innerElem.appendChild(thumbnailElem);
 
   // The button used to blacklist this page.
   var blacklistButton = createAndAppendElement(
       innerElem, 'div', CLASSES.BLACKLIST_BUTTON);
   createAndAppendElement(
@@ skipping 458 matching lines @@
 
 return {
   init: init,
   listen: listen
 };
 }
 
 if (!window.localNTPUnitTest) {
   LocalNTP().listen();
 }