root/chrome/browser/extensions/api/sync_file_system/

1. extension_sync_event_observer.cc
2. extension_sync_event_observer.h
3. sync_file_system_api.cc
4. sync_file_system_api.h
5. sync_file_system_api_helpers.cc
6. sync_file_system_api_helpers.h
7. sync_file_system_apitest.cc