GitLab

Checks if a test has the PRE_ prefix. Use it for tests that wants to
know, so they do not have to have their own version.

Change-Id: I4c0dbf38ab5c3ab5b088b5564a91acc61f275656
Reviewed-on: https://chromium-review.googlesource.com/786771
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#519753}