Dynamically generate a heading for Extension Docs API pages

chrome/common/extensions/api/alarms.idl

Index: chrome/common/extensions/api/alarms.idl
diff --git a/chrome/common/extensions/api/alarms.idl b/chrome/common/extensions/api/alarms.idl
index 47ccb2a61979081c1db863c3aac79b79b99bf2fe..813958e84b0803fbb19615083ac9d6c74025be22 100644
--- a/chrome/common/extensions/api/alarms.idl
+++ b/chrome/common/extensions/api/alarms.idl
@@ -1,9 +1,12 @@
 // 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.
-
 // TODO(mpcomplete): We need documentation before we can release this.
 
+// Use the <code>chrome.alarms</code> module to schedule code to run
+// periodically or at a specified time in the future.
+
+[availability=22]
 namespace alarms {
   dictionary Alarm {
     // Name of this alarm.