perf_uploader: send 'higher_is_better' info to dashboard

Currently perf dashboard guess higher or lower is better based
on unit associated with perf value. This CL send the info to
the dashboard to remove guesswork by adding this info to the
json that will be uploaded to the server.

BUG=chromium:280649
TEST=Add higher_is_better to expected json output in unittest
then run perf_uploader_unittest.py. Unittest passed.

Change-Id: Ic5a3e095ab2152682e025a8c80e52b6131aeb14d
Reviewed-on: https://chromium-review.googlesource.com/200330
Reviewed-by: Quinten Yearsley <qyearsley@google.com>
Commit-Queue: Quinten Yearsley <qyearsley@google.com>
Tested-by: Quinten Yearsley <qyearsley@google.com>
Reviewed-by: Fang Deng <fdeng@chromium.org>
2 files changed