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

ppapi/native_client/tests/ppapi_messaging/ppapi_messaging.c

 /*
- * 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 <stdio.h>
 #include <string.h>
 
 #include "native_client/src/include/portability.h"
 #include "native_client/src/shared/platform/nacl_check.h"
 #include "ppapi/c/pp_completion_callback.h"
@@ skipping 130 matching lines @@
     return &instance_interface;
   } else if (0 == strncmp(PPP_MESSAGING_INTERFACE, interface_name,
                           strlen(PPP_MESSAGING_INTERFACE))) {
     static struct PPP_Messaging messaging_interface = {
       HandleMessage
     };
     return &messaging_interface;
   }
   return NULL;
 }