Add tests for if codec info surfaces at the right time.
In support of landing this spec PR:
w3c/webrtc-pc#2972
Bug: None
Change-Id: I698276ccf739a872d791fc0923c2725ec303fbd3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5642762
Commit-Queue: Harald Alvestrand hta@chromium.org
Reviewed-by: Florent Castelli orphis@chromium.org
Cr-Commit-Position: refs/heads/main@{#1317347}