Re-land alexbost's experimental Offscreen Tabs API work.

chrome/common/extensions/docs/js/api_page_generator.js

 // Copyright (c) 2012 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.
 
 /**
  * @fileoverview This file is the controller for generating extension
  * doc pages.
  *
  * It expects to have available via XHR (relative path):
  *   1) API_TEMPLATE which is the main template for the api pages.
@@ skipping 22 matching lines @@
   '../api/experimental.accessibility.json',
   '../api/experimental.app.json',
   '../api/experimental.bookmarkManager.json',
   '../api/experimental.clear.json',
   '../api/experimental.dns.json',
   '../api/experimental.downloads.json',
   '../api/experimental.infobars.json',
   '../api/experimental.input.ime.json',
   '../api/experimental.input.ui.json',
   '../api/experimental.input.virtualKeyboard.json',
+  '../api/experimental.offscreenTabs.json',
   '../api/experimental.privacy.json',
   '../api/experimental.processes.json',
   '../api/experimental.rlz.json',
   '../api/experimental.serial.json',
   '../api/experimental.socket.json',
   '../api/experimental.speechInput.json',
   '../api/experimental.storage.json',
   '../api/experimental.topSites.json',
   '../api/extension.json',
   '../api/fileBrowserHandler.json',
@@ skipping 576 matching lines @@
 
 function sortByName(a, b) {
   if (a.name < b.name) {
     return -1;
   }
   if (a.name > b.name) {
     return 1;
   }
   return 0;
 }