Make generate_buildbot_json_coveragetest mandatory.

coverage is now part of Chromium's vpython spec. This script is
crucial to Chrome's infrastructure, and changes should not be allowed
unless the standard of code coverage is maintained.

Bug: 843842, 662541, 792130
Change-Id: I9164fe331045d13e08c1e1d40c79a01bac368ff9
Reviewed-on: https://chromium-review.googlesource.com/1063257
Reviewed-by: John Budorick <jbudorick@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#559711}
1 file changed