Update references to the extension messaging APIs to point to the "runtime"

chrome/common/extensions/docs/examples/extensions/catifier/event_page.js

 // Copyright (c) 2012 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.
 
 // Sample extension to replace all JPEG images (but no PNG/GIF/... images) with
 // lolcat images from http://icanhascheezburger.com/ - except for images on
 // Google.
 
 var RequestMatcher = chrome.declarativeWebRequest.RequestMatcher;
 var IgnoreRules = chrome.declarativeWebRequest.IgnoreRules;
@@ skipping 29 matching lines @@
     conditions: [
       // We use hostContains to compensate for various top-level domains.
       new RequestMatcher({url: {hostContains: '.google.'}})
     ],
     actions: [
       new IgnoreRules({lowerPriorityThan: 1000})
     ]
   };
 
   var callback = function() {
-    if (chrome.extension.lastError) {
-      console.error('Error adding rules: ' + chrome.extension.lastError);
+    if (chrome.runtime.lastError) {
+      console.error('Error adding rules: ' + chrome.runtime.lastError);
     } else {
       console.info('Rules successfully installed');
       chrome.declarativeWebRequest.onRequest.getRules(null,
           function(rules) {
             console.info('Now the following rules are registered: ' +
                          JSON.stringify(rules, null, 2));
           });
     }
   };
 
   chrome.declarativeWebRequest.onRequest.addRules(
       [redirectRule, exceptionRule], callback);
 }
 
 function setup() {
   // This function is also called when the extension has been updated.  Because
   // registered rules are persisted beyond browser restarts, we remove
   // previously registered rules before registering new ones.
   chrome.declarativeWebRequest.onRequest.removeRules(
     null,
     function() {
-      if (chrome.extension.lastError) {
-        console.error('Error clearing rules: ' + chrome.extension.lastError);
+      if (chrome.runtime.lastError) {
+        console.error('Error clearing rules: ' + chrome.runtime.lastError);
       } else {
         registerRules();
       }
     });
 }
 
 // This is triggered when the extension is installed or updated.
 chrome.runtime.onInstalled.addListener(setup);