crosperf: clean lint warning for results_report.py

BUG=chromium:567921
TEST=it is lint warning free now.

Change-Id: I623851a3420033f9a43e92c77423479c5cd766d9
Reviewed-on: https://chrome-internal-review.googlesource.com/241528
Commit-Ready: Yunlian Jiang <yunlian@google.com>
Tested-by: Yunlian Jiang <yunlian@google.com>
Reviewed-by: Yunlian Jiang <yunlian@google.com>
2 files changed