root/chrome/browser/extensions/api/media_galleries_private/

1. gallery_watch_manager.cc
2. gallery_watch_manager.h
3. gallery_watch_state_tracker.cc
4. gallery_watch_state_tracker.h
5. media_galleries_private_api.cc
6. media_galleries_private_api.h
7. media_galleries_private_event_router.cc
8. media_galleries_private_event_router.h
9. media_galleries_watch_apitest.cc