Work on GN build of Chrome.

components/copresence.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.
 
 {
   'targets': [
     {
       'target_name': 'copresence',
       'type': 'static_library',
       'dependencies': [
         '../base/base.gyp:base',
         '../content/content.gyp:content_common',
         '../media/media.gyp:media',
         '../media/media.gyp:shared_memory_support',
         '../net/net.gyp:net',
         'copresence_proto',
       ],
       'include_dirs': [
         '..',
       ],
       'sources': [
+        # Note: sources list duplicated in GN build.
         'copresence/copresence_constants.cc',
         'copresence/copresence_manager.cc',
         'copresence/copresence_manager_impl.cc',
         'copresence/copresence_switches.cc',
         'copresence/copresence_switches.h',
         'copresence/handlers/audio/audio_directive_handler.cc',
         'copresence/handlers/audio/audio_directive_handler.h',
         'copresence/handlers/audio/audio_directive_list.cc',
         'copresence/handlers/audio/audio_directive_list.h',
         'copresence/handlers/directive_handler.cc',
@@ skipping 43 matching lines @@
         'copresence/proto/rpcs.proto',
       ],
       'variables': {
         'proto_in_dir': 'copresence/proto',
         'proto_out_dir': 'components/copresence/proto',
       },
       'includes': [ '../build/protoc.gypi' ]
     },
   ],
 }