Catch exception when creating device log entries

chrome/browser/resources/device_log_ui/device_log_ui.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.
 
 var DeviceLogUI = (function() {
   'use strict';
 
   /**
    * Creates a tag for the log level.
    *
@@ skipping 77 matching lines @@
         container.appendChild(entry);
     }
   };
 
   /**
    * Callback function, triggered when the log is received.
    *
    * @param {Object} data A JSON structure of event log entries.
    */
   var getLogCallback = function(data) {
-    createEventLog(JSON.parse(data));
+    try {
+      createEventLog(JSON.parse(data));
+    } catch(e) {
+      var container = $('log-container');
+      container.textContent = 'No log entries';
+    }
   };
 
   /**
    * Requests a log update.
    */
   var requestLog = function() {
     chrome.send('DeviceLog.getLog');
   };
 
   /**
@@ skipping 31 matching lines @@
       checkboxes[i].onclick = requestLog;
 
     setRefresh();
     requestLog();
   });
 
   return {
     getLogCallback: getLogCallback
   };
 })();