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

chrome/common/extensions/docs/templates/intros/experimental_speechInput.html

 <p id="classSummary">
 The <code>chrome.experimental.speechInput</code> module provides
 one-shot speech recognition to Chrome extensions.
 This module is still experimental. For information on how to use experimental
 APIs, see the <a href="experimental.html">chrome.experimental.* APIs</a> page.
 </p>
 
 <h2 id="manifest">Manifest</h2>
 <p>You must declare the "experimental" permission in the <a
   href="manifest.html">extension manifest</a> to use the speech input
 API.
 For example:</p>
 <pre>{
   "name": "My extension",
   ...
   <b>"permissions": [
     "experimental"
   ]</b>,
   ...
 }</pre>
 
 <h2 id="howToStart">How to start speech recognition</h2>
 <p>To start recognizing speech an extension must call the <code>start()</code>
 method. If provided, your callback will be called once recording has
-successfully started. In case of error <code>chrome.extension.lastError</code>
+successfully started. In case of error <code>chrome.runtime.lastError</code>
 will be set.</p>
 
 <p>This API provides exclusive access to the default recording device to the
 first extension requesting it. Consequently, any calls to <code>start()</code>
 when the device is being used by another extension or web page will fail and set
-<code>chrome.extension.lastError</code>. The message <code>requestDenied</code>
+<code>chrome.runtime.lastError</code>. The message <code>requestDenied</code>
 will be set if another extension in the same profile is making use of the API.
 Otherwise <code>noRecordingDeviceFound</code>, <code>recordingDeviceInUse</code>
 or <code>unableToStart</code> will be set depending on the situation.</p>
 
 <p>To check whether recording is currently active, call the
 <code>isRecording()</code> method. Please note that it only checks for audio
 recording within Chrome.</p>
 
 
 <h2 id="howToGetResults">How to get speech recognition results</h2>
@@ skipping 22 matching lines @@
 chrome.experimental.speechInput.onError.addListener(callback);
 </pre>
 
 </p>Recording will automatically stop in case of error.
 It is safe to call <code>start()</code> again from the error callback.</p>
 
 
 <h2 id="howToStop">How to stop recording</h2>
 <p>To stop speech recognition call the <code>stop()</code> method. If provided,
 the callback function will be called once recording has successfully stopped.
-In case of error <code>chrome.extension.lastError</code> will be set.
+In case of error <code>chrome.runtime.lastError</code> will be set.
 </p>
 
 
 <h2 id="otherFeatures">Other features</h2>
 <ul><li>
 <code>onSoundStart</code> - Event generated when start of sound is detected
 (from previously being silent).
 </li><li>
 <code>onSoundEnd</code> - Event generated when end of sound is detected (a
 continued period of silence).
 </li></ul>
 
 
 <h2 id="examples">Examples</h2>
 <p>The following example illustrates how to show a JavaScript alert with the
 most likely recognition result.</p>
 <pre>
 function checkStart() {
-  if (chrome.extension.lastError) {
-    alert("Couldn't start speech input: " + chrome.extension.lastError.message);
+  if (chrome.runtime.lastError) {
+    alert("Couldn't start speech input: " + chrome.runtime.lastError.message);
   }
 }
 
 function recognitionFailed(error) {
   alert("Speech input failed: " + error.code);
 }
 
 function recognitionSucceeded(result) {
   alert("Recognized '" + result.hypotheses[0].utterance + "' with confidence " + result.hypotheses[0].confidence);
 }
 
 chrome.experimental.speechInput.onError.addListener(recognitionFailed);
 chrome.experimental.speechInput.onResult.addListener(recognitionSucceeded);
 chrome.experimental.speechInput.start({ "language": "en" }, checkStart);
-</pre>
+</pre>