Adding the message writing class used for remote_security_key STDOUT communication.

remoting/host/BUILD.gn

 # 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.
 
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/util/version.gni")
 import("//remoting/remoting_host.gni")
 import("//remoting/remoting_locales.gni")
 import("//remoting/remoting_options.gni")
@@ skipping 275 matching lines @@
       "register_support_host_request_unittest.cc",
       "remote_input_filter_unittest.cc",
       "resizing_host_observer_unittest.cc",
       "resources_unittest.cc",
       "screen_resolution_unittest.cc",
       "security_key/gnubby_auth_handler_linux_unittest.cc",
       "security_key/gnubby_auth_handler_win_unittest.cc",
       "security_key/gnubby_extension_session_unittest.cc",
       "security_key/remote_security_key_ipc_client_unittest.cc",
       "security_key/remote_security_key_ipc_server_unittest.cc",
+      "security_key/remote_security_key_message_writer_unittest.cc",
       "server_log_entry_host_unittest.cc",
       "setup/me2me_native_messaging_host_unittest.cc",
       "setup/oauth_helper_unittest.cc",
       "setup/pin_validator_unittest.cc",
       "third_party_auth_config_unittest.cc",
       "token_validator_factory_impl_unittest.cc",
       "touch_injector_win_unittest.cc",
       "video_frame_recorder_unittest.cc",
       "win/rdp_client_unittest.cc",
       "win/worker_process_launcher_unittest.cc",
@@ skipping 342 matching lines @@
           "//remoting/resources",
           "//third_party/icu:icudata",
         ]
       }
     } else {
       group("remoting_me2me_host_archive") {
       }
     }
   }
 }