[1] https://developers.google.com/cast/docs/reference/chrome/chrome.cast#.AutoJoinPolicy

Hm, I think we supported AutoJoinPolicy on Android from the beginning, see here: https://cs.chromium.org/chromium/src/chrome/android/java/src/org/chromium/chrome/browser/media/router/cast/CastMediaRouteProvider.java?rcl=0&l=479

I believe this was reported by a developer trying to use it, and it wasn't working as expected.

Can you manually verify it works?

We pass the auto join integration tests run against both Clank and desktop. Could you find the report? I recall someone complaining that joining a Cast session launched from a different browser instance (e.g. another device) didn't work.
This would be a different issue though so I would rename the bug and change it's summary.

Any update?

I think we're waiting for steps to reproduce (or pointer to an external report that has the same).

Assigning to myself to repro or close.

Never a confirmed issue.  Closing.