Enable chrome://gcm-internals on Android

components/gcm_driver/resources/gcm_internals.js

 // Copyright 2014 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.
 
 cr.define('gcmInternals', function() {
   'use strict';
 
   var isRecording = false;
 
   /**
    * If the info dictionary has property prop, then set the text content of
    * element to the value of this property. Otherwise clear the content.
    * @param {!Object} info A dictionary of device infos to be displayed.
    * @param {string} prop Name of the property.
-   * @param {string} element The id of a HTML element.
+   * @param {string} elementId The id of a HTML element.
    */
-  function setIfExists(info, prop, element) {
+  function setIfExists(info, prop, elementId) {
+    var element = $(elementId);
+    if (!element)
+      return;
+
     if (info[prop] !== undefined) {
-      $(element).textContent = info[prop];
+      element.textContent = info[prop];
     } else {
-      $(element).textContent = '';
+      element.textContent = '';
     }
   }
 
   /**
    * Display device informations.
    * @param {!Object} info A dictionary of device infos to be displayed.
    */
   function displayDeviceInfo(info) {
     setIfExists(info, 'androidId', 'android-id');
     setIfExists(info, 'profileServiceCreated', 'profile-service-created');
@@ skipping 67 matching lines @@
     $('recording').disabled = true;
     $('refresh').onclick = refreshAll;
     $('recording').onclick = setRecording;
     $('clear-logs').onclick = clearLogs;
     chrome.send('getGcmInternalsInfo', [false]);
   }
 
   /**
    * Refresh the log html table by clearing it first. If data is not empty, then
    * it will be used to populate the table.
-   * @param {string} id ID of the log html table.
+   * @param {string} tableId ID of the log html table.
    * @param {!Object} data A list of list of data items.
    */
-  function refreshLogTable(id, data) {
-    removeAllChildNodes($(id));
-    if (data !== undefined) {
-      addRows($(id), data);
-    }
+  function refreshLogTable(tableId, data) {
+    var element = $(tableId);
+    if (!element)
+      return;
+
+    removeAllChildNodes(element);
+    if (data !== undefined)
+      addRows(element, data);
   }
 
   /**
    * Callback function accepting a dictionary of info items to be displayed.
    * @param {!Object} infos A dictionary of info items to be displayed.
    */
   function setGcmInternalsInfo(infos) {
     isRecording = infos.isRecording;
     if (isRecording)
       $('recording').textContent = 'Stop Recording';
@@ skipping 12 matching lines @@
   }
 
   // Return an object with all of the exports.
   return {
     initialize: initialize,
     setGcmInternalsInfo: setGcmInternalsInfo,
   };
 });
 
 document.addEventListener('DOMContentLoaded', gcmInternals.initialize);