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

chrome/test/data/extensions/api_test/speech_input/start_error/test.js

 // Copyright (c) 2011 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.
 
 // Extension Speech Input api test.
 // browser_tests --gtest_filter="ExtensionSpeechInputApiTest.*"
 
 chrome.test.runTests([
   function testSpeechInputStartError() {
 
     // Recording is not active, start it.
     chrome.experimental.speechInput.isRecording(function(recording) {
       chrome.test.assertNoLastError();
       chrome.test.assertFalse(recording);
       chrome.experimental.speechInput.start({}, started);
     });
 
     // Start should fail because no devices are available.
     function started() {
-      chrome.test.assertEq(chrome.extension.lastError.message,
+      chrome.test.assertEq(chrome.runtime.lastError.message,
           "noRecordingDeviceFound");
 
       // Recording shouldn't have started.
       chrome.experimental.speechInput.isRecording(function(recording) {
         chrome.test.assertNoLastError();
         chrome.test.assertFalse(recording);
 
         // Stopping should fail since we're back in the idle state.
         chrome.experimental.speechInput.stop(function() {
-          chrome.test.assertEq(chrome.extension.lastError.message,
+          chrome.test.assertEq(chrome.runtime.lastError.message,
               "invalidOperation");
           chrome.test.succeed();
         });
       });
     }
   }
 ]);