Pepper: Move DoPostMessage out of trusted plugin.

ppapi/api/private/ppb_nacl_private.idl

 /* 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.
  */
 
 /* This file contains NaCl private interfaces. This interface is not versioned
  * and is for internal Chrome use. It may change without notice. */
 
 label Chrome {
   M25 = 1.0
@@ skipping 428 matching lines @@
   PP_Bool GetPnaclResourceInfo([in] PP_Instance instance,
                                [in] str_t filename,
                                [out] PP_Var llc_tool_name,
                                [out] PP_Var ld_tool_name);
 
   // PP_Var string of attributes describing the CPU features supported
   // by the current architecture. The string is a comma-delimited list
   // of attributes supported by LLVM in its -mattr= option:
   //   http://llvm.org/docs/CommandGuide/llc.html#cmdoption-mattr
   PP_Var GetCpuFeatureAttrs();
+
+  /* Posts a message to the JavaScript object for the given instance.
+   * This method may be called on any thread.
+   */
+  void PostMessageToJavaScript([in] PP_Instance instance,
+                               [in] str_t message);
 };