[sync] Componentize switches used by ProfileSyncService

components/browser_sync.gypi

 # Copyright 2015 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': 'child',
+      # GN version: //components/browser_sync_common
+      'target_name': 'browser_sync_common',
       'type': 'static_library',
-      'variables': { 'enable_wexit_time_destructors': 1, },
       'dependencies': [
         '../base/base.gyp:base',
-        '../content/content.gyp:content_child',
       ],
       'include_dirs': [
         '..',
       ],
       'sources': [
-        'child/pdf_child_init.cc',
-        'child/pdf_child_init.h',
+        # Note: file list duplicated in GN build.
+        'browser_sync/common/browser_sync_switches.cc',
+        'browser_sync/common/browser_sync_switches.h',
       ],
     },
   ],
 }