Update Blink to use environment clock timestamps from RTCStats objects.
https://webrtc-review.googlesource.com/c/src/+/363946 added a config flag to tell WebRTC to set environment clock timestamps in RTCStats objects (rather then UTC timestamps). This CL set the config flag, and update the code to handle the new timestamps.
This change make all RTCStats timestamps be expressed as Performance time, fixing chromium:369369568.
Bug: chromium:369369568
Change-Id: Icc991ba55543bf13a17b526a1247043551e85bab
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5920098
Commit-Queue: Olov Brändström brandstrom@chromium.org
Reviewed-by: Harald Alvestrand hta@chromium.org
Reviewed-by: Henrik Boström hbos@chromium.org
Reviewed-by: Johannes Kron kron@chromium.org
Cr-Commit-Position: refs/heads/main@{#1368191}