I'll probably update the recipe or trybot command to just always force that flag on, each person running this shouldn't have to know to add that format.

SGTM. thanks.

Also notes that Ben is making HTML format the default. Though probably forcing the flag is still nice for strong guarantee.

run_benchmark produces html when either --output-format=html is specified, or no --output-format is specified.
Committed CL: https://codereview.chromium.org/3008123002

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/094d0cd98c2a77700a004ada7cfe8d1cc0e92646

commit 094d0cd98c2a77700a004ada7cfe8d1cc0e92646
Author: Simon <simonhatch@chromium.org>
Date: Wed Sep 13 16:20:22 2017

Perf Try - Add --output-format=html to all jobs.

For perf try jobs, you must specify --output-format=html in order to produce an HTML results file that can be displayed on the build page. 

This CL adds the flag if no --output-format is specified, or if none of the existing formats is html.

Bug: chromium:762570
Change-Id: I5e39937faa64fa7d6bfb2a643e22eac426ff17b1
Reviewed-on: https://chromium-review.googlesource.com/661056
Reviewed-by: Annie Sullivan <sullivan@chromium.org>
Commit-Queue: Simon Hatch <simonhatch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#501653}
[modify] https://crrev.com/094d0cd98c2a77700a004ada7cfe8d1cc0e92646/tools/perf/core/trybot_command.py
[modify] https://crrev.com/094d0cd98c2a77700a004ada7cfe8d1cc0e92646/tools/perf/core/trybot_command_unittest.py