Add abs(av_sync) metric to performance_browser_tests, to fix alerting.

The performance monitoring infrastructure assumes "lower is better," but
for the case of Audio/Video synchronization "closer to zero is better."
This adds an additional metric to provide the absolute value of the AV
sync measurement. The plan is to stop alerting on the existing AV sync
metric, and instead alert on this new one where "lower is better."

Change-Id: I47d2ad796edf43266577f9967b8e0957ae19a48b
Reviewed-on: https://chromium-review.googlesource.com/c/1405983
Reviewed-by: Caleb Rouleau <crouleau@chromium.org>
Commit-Queue: Yuri Wiitala <miu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#621802}
1 file changed