After https://webrtc-review.googlesource.com/c/src/+/329141, best candidate can still be less than acked rate if not_increase_if_inherent_loss_less_than_average_loss, or the selected candidate is 95% of current estimate. This cl/ is ensure the previous cl works as intended. And add unit test. Bug: webrtc:12707 Change-Id: Ie5683ca8ea51f6d80c4c59cbf08c22e8b24c0cb9 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/329441 Commit-Queue: Diep Bui <diepbp@webrtc.org> Reviewed-by: Per Kjellander <perkj@webrtc.org> Cr-Commit-Position: refs/heads/main@{#41298}