Adding the message writing class used for remote_security_key STDOUT communication.

remoting/remoting_host_srcs.gypi

 # 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.
 
 {
   'variables': {
     'remoting_host_sources': [
       'host/audio_capturer.cc',
       'host/audio_capturer.h',
       'host/audio_capturer_linux.cc',
@@ skipping 208 matching lines @@
       'host/security_key/gnubby_socket.cc',
       'host/security_key/gnubby_socket.h',
       'host/security_key/remote_security_key_ipc_client.cc',
       'host/security_key/remote_security_key_ipc_client.h',
       'host/security_key/remote_security_key_ipc_constants.cc',
       'host/security_key/remote_security_key_ipc_constants.h',
       'host/security_key/remote_security_key_ipc_server.cc',
       'host/security_key/remote_security_key_ipc_server.h',
       'host/security_key/remote_security_key_ipc_server_impl.cc',
       'host/security_key/remote_security_key_ipc_server_impl.h',
+      'host/security_key/remote_security_key_message_writer.cc',
+      'host/security_key/remote_security_key_message_writer.h',
       'host/security_key/security_key_message.cc',
       'host/security_key/security_key_message.h',
       'host/server_log_entry_host.cc',
       'host/server_log_entry_host.h',
       'host/service_urls.cc',
       'host/service_urls.h',
       'host/shutdown_watchdog.cc',
       'host/shutdown_watchdog.h',
       'host/signaling_connector.cc',
       'host/signaling_connector.h',
@@ skipping 96 matching lines @@
       'host/it2me/it2me_confirmation_dialog_chromeos.cc',
       'host/it2me/it2me_confirmation_dialog_proxy.cc',
       'host/it2me/it2me_confirmation_dialog_proxy.h',
       'host/it2me/it2me_host.cc',
       'host/it2me/it2me_host.h',
       'host/it2me/it2me_native_messaging_host.cc',
       'host/it2me/it2me_native_messaging_host.h',
     ],
   }
 }