We knew that we should not update buffer level during DTX period. We already fulfill this upon no packet receipt. But we missed doing it for DTX-signaling packets. This CL is to fix that. Bug: b/129521878 Change-Id: I72ca18e3b21e956123fe6e3119ef0d7c981c9eec Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/133183 Commit-Queue: Minyue Li <minyue@webrtc.org> Reviewed-by: Jakob Ivarsson <jakobi@webrtc.org> Reviewed-by: Henrik Lundin <henrik.lundin@webrtc.org> Cr-Commit-Position: refs/heads/master@{#27643}