Add empty list indicator for Physical Web WebUI

components/physical_web/webui/resources/physical_web.js

Index: components/physical_web/webui/resources/physical_web.js
diff --git a/components/physical_web/webui/resources/physical_web.js b/components/physical_web/webui/resources/physical_web.js
index 418dc1d6e90c1b5e8daffb35b8fbd841900eae08..70d856fe7db71a2222280e9cda9630a922507d4b 100644
--- a/components/physical_web/webui/resources/physical_web.js
+++ b/components/physical_web/webui/resources/physical_web.js
@@ -24,8 +24,12 @@ function physicalWebItemClicked(index) {
 function returnNearbyURLs(nearbyUrlsData) {
   var bodyContainer = $('body-container');
   renderTemplate(nearbyUrlsData);
+  bodyContainer.hidden = false;

[mmocny, 2017/03/09 23:22:32]

Nit: I know that if the result length is 0 that this body will be empty, but
should we really be showing it?

If yes, why did we make it hidden in the first place?

if no, could we make this hidden = false inside an else block below?

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