Spun off from https://bugs.chromium.org/p/chromium/issues/detail?id=586656#c6:

The root cause for this bug was that we had two clock implementations, with different behavior on some platforms. As the fix was to remove one of them (webrtc::Clock is now a wrapper that just calls rtc::Time), adding tests for that specific issue doesn't seem very useful.
That said, we could probably add browser test to sanity check the stats we output. For instance delays not being smaller than 0 or greater than.. something very large.