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

chrome/common/extensions/docs/examples/api/speechInput/basic/background.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.
 
 function setStartIcon() {
   chrome.browserAction.setIcon({ path: "start.png" });
 }
 
 function setStopIcon() {
   chrome.browserAction.setIcon({ path: "stop.png" });
 }
 
 chrome.browserAction.onClicked.addListener(function(tab) {
   chrome.experimental.speechInput.isRecording(function(recording) {
     if (!recording) {
       chrome.experimental.speechInput.start({}, function() {
-        if (chrome.extension.lastError) {
+        if (chrome.runtime.lastError) {
           alert("Couldn't start speech input: " +
-              chrome.extension.lastError.message);
+              chrome.runtime.lastError.message);
           setStartIcon();
         } else {
           setStopIcon();
         }
       });
     } else {
       chrome.experimental.speechInput.stop(function() {
         setStartIcon();
       });
     }
   });
 });
 
 chrome.experimental.speechInput.onError.addListener(function(error) {
   alert("Speech input failed: " + error.code);
   setStartIcon();
 });
 
 chrome.experimental.speechInput.onResult.addListener(function(result) {
   alert(result.hypotheses[0].utterance);
   setStartIcon();
 });