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

chrome/test/data/extensions/api_test/speech_input/start_stop/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 testSpeechInputStartStop() {
     var count = 0;
@@ skipping 26 matching lines @@
           chrome.experimental.speechInput.start({}, started);
         else
           chrome.test.succeed();
       });
     }
   },
 
   function testSpeechInputInvalidOperation() {
     // Calling start once recording should generate an invalid operation error.
     chrome.experimental.speechInput.stop(function() {
-      chrome.test.assertEq(chrome.extension.lastError.message,
+      chrome.test.assertEq(chrome.runtime.lastError.message,
           "invalidOperation");
       chrome.experimental.speechInput.start({}, started);
     });
 
     // Calling stop before recording should generate an invalid operation error.
     function started() {
       chrome.test.assertNoLastError();
       chrome.experimental.speechInput.start({}, function() {
-        chrome.test.assertEq(chrome.extension.lastError.message,
+        chrome.test.assertEq(chrome.runtime.lastError.message,
             "invalidOperation");
         chrome.test.succeed();
       });
     }
   }
 ]);