Move the `privacy` extension API out of experimental.

chrome/common/extensions/docs/static/manifest.html

 <div id="pageData-name" class="pageData">Formats: Manifest Files</div>
 <div id="pageData-showTOC" class="pageData">true</div>
 
 <p>
 Every extension, installable web app, and theme has a
 <a href="http://www.json.org">JSON</a>-formatted manifest file,
 named <code>manifest.json</code>,
 that provides important information.
 </p>
 
@@ skipping 548 matching lines @@
 <tr>
   <td> "notifications" </td>
   <td> Allows the extension to use the proposed HTML5
        <a href="http://www.chromium.org/developers/design-documents/desktop-notifications/api-specification">notification API</a>
        without calling permission methods
        (such as <code>checkPermission()</code>).
        For more information see
        <a href="notifications.html">Desktop Notifications</a>.</td>
 </tr>
 <tr>
+  <td> "privacy" </td>
+  <td> Required if the extension uses the
+       <a href="privacy.html">chrome.privacy</a> module. </td>
+</tr>
+<tr>
   <td> "proxy" </td>
   <td> Required if the extension uses the
        <a href="proxy.html">chrome.proxy</a> module. </td>
 </tr>
 <tr>
   <td> "tabs" </td>
   <td> Required if the extension uses the
        <a href="tabs.html">chrome.tabs</a> or
        <a href="windows.html">chrome.windows</a> module. </td>
 </tr>
@@ skipping 138 matching lines @@
 
 <pre>"manifest_version": 2</pre>
 
 <p>
 Future breaking changes to the extension system may require a new version
 number.
 </p>
 
 
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