Add Physical Web WebUI Default Url Icon

components/physical_web/webui/resources/physical_web.js

 // Copyright (c) 2016 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.
 
 /**
  * Takes the |nearbyUrlsData| input argument which holds metadata for web pages
  * broadcast by nearby devices.
  * @param {Object} nearbyUrlsData Information about web pages broadcast by
  *      nearby devices
  */
 function renderTemplate(nearbyUrlsData) {
   // This is the javascript code that processes the template:
   jstProcess(new JsEvalContext(nearbyUrlsData), $('physicalWebTemplate'));
 }
 
 function requestNearbyURLs() {
   chrome.send('requestNearbyURLs');
 }
 
 function physicalWebItemClicked(index) {
   chrome.send('physicalWebItemClicked', [index]);
 }
 
 function returnNearbyURLs(nearbyUrlsData) {
   var bodyContainer = $('body-container');
   renderTemplate(nearbyUrlsData);
+  bodyContainer.style.visibility = 'visible';
+  addErrorHandler();
+}
 
-  bodyContainer.style.visibility = 'visible';
+function addErrorHandler() {
+  var images = document.getElementsByTagName('img');

[mattreynolds, 2017/02/28 22:20:54]

Can we make this only match favicon images? If we add any other error-prone
images to the page this will catch them too.

+  for (var i = 0; i < images.length; i++) {

[cco3, 2017/02/28 22:10:49]

I know you are working with some old version of jquery, but you should be able
to do:

$('img').foreach(function() {
    $(this).addEventListener(...)
});

+    var img = images[i];
+    img.addEventListener('error', function() {
+      this.src = "chrome://physical-web/link.png";
+    });
+  }
 }
 
 document.addEventListener('DOMContentLoaded', requestNearbyURLs);