Brad Fitzpatrick 052602752f control/controlclient: make Observer optional
As a baby step towards eventbus-ifying controlclient, make the
Observer optional.

This also means callers that don't care (like this network lock test,
and some tests in other repos) can omit it, rather than passing in a
no-op one.

Updates #12639

Change-Id: Ibd776b45b4425c08db19405bc3172b238e87da4e
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2025-11-14 10:40:41 -08:00
..