rebaseline_server: add "prefetch" directive that just warms the cache without awaiting results
This will allow the buildbots to warn the production rebaseline_server: "I just
generated some new results; here's a comparison that a human might ask for
soon. Download whatever images and generate whatever diffs you would need to
provide those results."
BUG=skia:1942
NOTREECHECKS=true
NOTRY=true
R=rmistry@google.com
Author: epoger@google.com
Review URL: https://codereview.chromium.org/443013002
5 files changed