GitLab

Make perf test generate LUCI test result json when trace is enabled
so that performance test script could pick it up and extract
metrics out of the trace file.

Test result json follows the TestResultEntry spec in LUCI Test
Results format (go/luci-test-results-design). Outputting in
this format will allow reusing the code for results processor (
https://docs.google.com/document/d/1GYiqUJGxdUWtg9YQMXEXSILylG4J2wpiGIZM8F-HD_U
) for gtest perf tests.

Bug: 945711
Change-Id: I405b3aeab1217d5f87a9c7d3eba8f5e8eabac4dc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1790122
Commit-Queue: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Brian Sheedy <bsheedy@chromium.org>
Reviewed-by: Juan Antonio Navarro Pérez <perezju@chromium.org>
Reviewed-by: Caleb Rouleau <crouleau@chromium.org>
Reviewed-by: Jao-ke Chin-Lee <jchinlee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#705302}