Update Native Client Authors to be Chromium Authors for the code moved from the

ppapi/native_client/src/shared/ppapi_proxy/plugin_ppb_messaging.cc

-// Copyright (c) 2011 The Native Client Authors. All rights reserved.
+// Copyright (c) 2011 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.
 
 #include "native_client/src/shared/ppapi_proxy/plugin_ppb_messaging.h"
 
 #include "native_client/src/include/nacl_scoped_ptr.h"
 #include "native_client/src/include/portability.h"
 #include "native_client/src/shared/ppapi_proxy/object_serialize.h"
 #include "native_client/src/shared/ppapi_proxy/plugin_globals.h"
 #include "native_client/src/shared/ppapi_proxy/utility.h"
@@ skipping 28 matching lines @@
 }  // namespace
 
 const PPB_Messaging* PluginMessaging::GetInterface() {
   static const PPB_Messaging  messaging_interface = {
     PostMessage
   };
   return &messaging_interface;
 }
 
 }  // namespace ppapi_proxy