This will be used to calculate a lower bound for the round trip time in a later CL. Bug: webrtc:9718 Change-Id: I0a1d22045961fe6bd343d1d6ce9b36490b036bb1 Reviewed-on: https://webrtc-review.googlesource.com/c/114680 Commit-Queue: Sebastian Jansson <srte@webrtc.org> Reviewed-by: Christoffer Rodbro <crodbro@webrtc.org> Cr-Commit-Position: refs/heads/master@{#26050}