This allows both the signal and the callback to be used. Bug: webrtc:11943 Change-Id: I89460126d415520295c7e7d4ee440156a6e9e5ab Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/329140 Reviewed-by: Per Kjellander <perkj@webrtc.org> Commit-Queue: Harald Alvestrand <hta@webrtc.org> Cr-Commit-Position: refs/heads/main@{#41282}