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

chrome/test/data/extensions/api_test/filesystem_handler_lazy_background/tab.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.
 
 // The ID of the extension we want to talk to.
 var fileBrowserExtensionId = "ddammdhioacbehjngdmkjcjbnfginlla";
 
 function errorCallback(error) {
   var msg = '';
   if (!error.code) {
@@ skipping 14 matching lines @@
         break;
       case FileError.INVALID_STATE_ERR:
         msg = 'INVALID_STATE_ERR';
         break;
       default:
         msg = 'Unknown Error';
         break;
     };
   }
 
-  chrome.extension.sendMessage(fileBrowserExtensionId,
+  chrome.runtime.sendMessage(fileBrowserExtensionId,
                                {fileContent: null,
                                 error: {message: "File handler error: " + msg}},
                                function(response) {});
 };
 
 function onGotEntryByUrl(entry) {
   var reader = new FileReader();
   reader.onloadend = function(e) {
     // Send data back to the file browser extension
-    chrome.extension.sendMessage(
+    chrome.runtime.sendMessage(
         fileBrowserExtensionId,
         {fileContent: reader.result, error: null},
         function(response) {});
   };
   reader.onerror = function(e) {
     errorCallback(reader.error);
   };
   entry.file(function(file) {
     reader.readAsText(file);
   },
   errorCallback);
 };
 
 function readEntryByUrl(entryUrl) {
   window.webkitResolveLocalFileSystemURL(entryUrl, onGotEntryByUrl,
                                          errorCallback);
 };
 
 readEntryByUrl(localStorage.entryURL);