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

chrome/browser/resources/local_ntp/local_ntp.js

Index: chrome/browser/resources/local_ntp/local_ntp.js
diff --git a/chrome/browser/resources/local_ntp/local_ntp.js b/chrome/browser/resources/local_ntp/local_ntp.js
index da790a12feebf2ca0b58047e2ef1c37c7e654a22..c02a2cf5f99a275e599cfc625f493d8f49dbd00b 100644
--- a/chrome/browser/resources/local_ntp/local_ntp.js
+++ b/chrome/browser/resources/local_ntp/local_ntp.js
@@ -698,6 +698,10 @@ function createTile(page, position) {
   // link element (which also has a tabindex).
   titleElem.tabIndex = '0';
 
+  // Make the iframe presentational for accessibility so screen readers perceive
+  // the iframe content as just part of the same page.
+  titleElem.setAttribute('role', 'presentation');
+
   // Why iframes have IDs:
   //
   // On navigating back to the NTP we see several onmostvisitedchange() events