Use event path to detect if anchor has been clicked in WebUIs.

ui/webui/resources/js/util.js

 // Copyright (c) 2012 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.
 
 // <include src="assert.js">
 
 /**
  * Alias for document.getElementById. Found elements must be HTMLElements.
  * @param {string} id The ID of the element to find.
  * @return {HTMLElement} The found element or null if not found.
@@ skipping 195 matching lines @@
  */
 function queryRequiredElement(selectors, opt_context) {
   var element = (opt_context || document).querySelector(selectors);
   return assertInstanceof(element, HTMLElement,
                           'Missing required element: ' + selectors);
 }
 
 // Handle click on a link. If the link points to a chrome: or file: url, then
 // call into the browser to do the navigation.
 document.addEventListener('click', function(e) {
   if (e.defaultPrevented)

[Dan Beam, 2016/08/02 06:02:44]

nit: in my ideal world

if (e.defaultPrevented || e.button > 1)
  return;

var link = e.path.find(el => el.tagName == 'A' && el.href);
if (!link || !['about:', 'file:'].includes(link.protocol))
  return;

chrome.send('navigateToUrl', [
  link.href,
  link.target,
  e.button,
  e.altKey,
  e.ctrlKey,
  e.metaKey,
  e.shiftKey
]);
e.preventDefault();

BUT =>, .find(), and .includes() wont work in Safari, so bollocks

[calamity, 2016/08/08 05:06:43]

Acknowledged.

     return;
 
-  var el = e.target;
-  if (el.nodeType == Node.ELEMENT_NODE &&
-      el.webkitMatchesSelector('A, A *')) {
-    while (el.tagName != 'A') {
-      el = el.parentElement;
+  var eventPath = e.path;

[Dan Beam, 2016/08/02 06:02:43]

this code runs on safari, which may have dodgy support for path (if any).  you
probably need to handle target as well or something...

[calamity, 2016/08/08 05:06:43]

Done.

+  var anchor = null;
+  for (var i = 0; i < eventPath.length; i++) {
+    var element = eventPath[i];
+    if (element.tagName === 'A' && element.href) {
+      anchor = element;
+      break;
     }
+  }
 
-    if ((el.protocol == 'file:' || el.protocol == 'about:') &&
-        (e.button == 0 || e.button == 1)) {
-      chrome.send('navigateToUrl', [
-        el.href,
-        el.target,
-        e.button,
-        e.altKey,
-        e.ctrlKey,
-        e.metaKey,
-        e.shiftKey
-      ]);
-      e.preventDefault();
-    }
+  if (!anchor)
+    return;
+
+  if ((anchor.protocol == 'file:' || anchor.protocol == 'about:') &&
+      (e.button == 0 || e.button == 1)) {
+    chrome.send('navigateToUrl', [
+      anchor.href,
+      anchor.target,
+      e.button,
+      e.altKey,
+      e.ctrlKey,
+      e.metaKey,
+      e.shiftKey
+    ]);
+    e.preventDefault();
   }
 });
 
 /**
  * Creates a new URL which is the old URL with a GET param of key=value.
  * @param {string} url The base URL. There is not sanity checking on the URL so
  *     it must be passed in a proper format.
  * @param {string} key The key of the param.
  * @param {string} value The value of the param.
  * @return {string} The new URL.
@@ skipping 183 matching lines @@
         case 0xdb: return '[';
         case 0xdd: return ']';
       }
       return 'Unidentified';
     }
   });
 } else {
   window.console.log("KeyboardEvent.Key polyfill not required");
 }
 // </if>  /* is_ios */