GitLab

Clean up render tests structure and require virtual time exhaustion as
an indication of rendering completion.

Change-Id: I62a7ed9389facaab223ab3ddebb80496ece5c203
Reviewed-on: https://chromium-review.googlesource.com/776517Reviewed-by: Alex Clarke <alexclarke@chromium.org>
Commit-Queue: Sergei Datsenko <dats@chromium.org>
Cr-Commit-Position: refs/heads/master@{#517813}