These macros replace a lot of repeated timing code, and mirror how
Chromium operates.

BUG=516027

Change-Id: Ib03e35d0f3b8638b9b0e8785c397c8381f16b041
Reviewed-on: https://chromium-review.googlesource.com/289995Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>