Add missing header files to GN files (2 of N)

remoting/host/win/BUILD.gn

 # Copyright 2016 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/toolchain/win/midl.gni")
 import("//build/win/message_compiler.gni")
 import("//media/media_options.gni")
 import("//remoting/build/config/remoting_build.gni")
 import("//remoting/host/installer/win/generate_clsids.gni")
 
@@ skipping 340 matching lines @@
     "//remoting/host/setup/host_starter.h",
     "//remoting/host/setup/me2me_native_messaging_host_main.cc",
     "//remoting/host/setup/me2me_native_messaging_host_main.h",
     "//remoting/host/setup/start_host_main.cc",
     "//remoting/host/setup/start_host_main.h",
     "//remoting/host/worker_process_ipc_delegate.h",
     "chromoting_lib.rc",
     "chromoting_module.cc",
     "chromoting_module.h",
     "core.cc",
+    "core.h",
     "core_resource.h",
     "elevated_native_messaging_host.cc",
     "elevated_native_messaging_host.h",
     "host_service.cc",
     "host_service.h",
     "launch_native_messaging_host_process.cc",
     "launch_native_messaging_host_process.h",
     "rdp_desktop_session.cc",
     "rdp_desktop_session.h",
     "unprivileged_process_delegate.cc",
@@ skipping 118 matching lines @@
 
   output = "$root_gen_dir/remoting/{{source_name_part}}"
 
   locale_dir = webapp_locale_dir
 
   encoding = "utf-16"
 
   locales = remoting_locales
 }
 # TODO(GYP) More Windows remoting targets from remoting_host_win.gypi