A followup to https://webrtc-review.googlesource.com/71380 and https://webrtc-review.googlesource.com/69986, deleting the nack_enabled flag. Bug: webrtc:8830 Change-Id: Ie53f7a1e131be5347936ed44cee7167295026d57 Reviewed-on: https://webrtc-review.googlesource.com/76760 Reviewed-by: Rasmus Brandt <brandtr@webrtc.org> Commit-Queue: Niels Moller <nisse@webrtc.org> Cr-Commit-Position: refs/heads/master@{#23256}