[Sylos]

Alright, status report.

The official documentation talks about the folders /chrome/browser/sync/engine, /chrome/browser/sync/syncable and /chrome/browser/sync/protocol.

These folders are missing from the source tree, as you can see here: https://chromium.googlesource.com/chromium/src.git/+/master/...

However, I decided to give the benefit of the doubt and did a few file-searches, in case the files were moved at some point and the documentation was just not updated.

And it seems like that's actually the case. The folder /sync contains all three missing folders (engine, syncable, protocol) and more: https://chromium.googlesource.com/chromium/src.git/+/master/...