See comment here: https://codereview.chromium.org/1767603003/diff/120001/chromecast/base/chromecast_switches_unittest.cc
Thanks for filing / taking this bug. Please use base::test::ScopedCommandLine instead. I have a pending CL to update the base::CommandLine::Reset() description to help avoid future situations like this.
Comment 1 by thestig@chromium.org
, Jul 15 2016