Uunit test code readability improvements. Bug: webrtc:12774 Change-Id: I66f552d23680ddb03824618dab869946e0940334 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/221900 Commit-Queue: Alessio Bazzica <alessiob@webrtc.org> Reviewed-by: Hanna Silen <silen@webrtc.org> Cr-Commit-Position: refs/heads/master@{#34300}