Add empty list indicator for Physical Web WebUI

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';

[cco3, 2017/02/23 23:36:54]

Just use the appropriate jquery method:
$('#body-container').show()

[cco3, 2017/02/23 23:39:33]

I saw your other comment.  This is definitely using some kind of jquery; `$` is
the jquery function.  You should be able to call show or .css('display, 'none').

I'm not sure why it would work without the #, but not with the hash.

[Ran, 2017/02/24 18:52:59]

The show and hide() function is not available, I guess it's not jQuery here.

 
-  bodyContainer.style.visibility = 'visible';
+  if (nearbyUrlsData['metadata'].length == 0) {
+    var emptyMessage = $('empty-container');
+    emptyMessage.style.visibility = 'visible';
+  }
 }
 
 document.addEventListener('DOMContentLoaded', requestNearbyURLs);