PPAPI: Move PPB_Messaging 1.2 to stable

ppapi/api/ppp_message_handler.idl

 /* Copyright 2014 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.
  */
 
 /**
  * This file defines the <code>PPP_MessageHandler</code> interface that plugins
  * can implement and register using PPB_Messaging::RegisterMessageHandler in
  * order to handle messages sent from JavaScript via postMessage() or
  * postMessageAndAwaitResponse().
  */
 
 label Chrome {
-  [channel=dev] M39 = 0.2
+  M39 = 0.2
 };
 
 /**
  * The <code>PPP_MessageHandler</code> interface is implemented by the plugin
  * if the plugin wants to receive messages from a thread other than the main
  * Pepper thread, or if the plugin wants to handle blocking messages which
  * JavaScript may send via postMessageAndAwaitResponse().
  *
  * This interface struct should not be returned by PPP_GetInterface; instead it
  * must be passed as a parameter to PPB_Messaging::RegisterMessageHandler.
@@ skipping 43 matching lines @@
    * and <code>user_data</code>.
    *
    * @param[in] instance A <code>PP_Instance</code> identifying one instance
    * of a module.
    * @param[in] user_data is the same pointer which was provided by a call to
    * RegisterMessageHandler.
    */
   void Destroy([in] PP_Instance instance, [inout] mem_t user_data);
 };