Project Grover: add wifi rate vs. range test case in Autotest.

BUG=chrome-os-partner:16414
TEST=Manual

Change-Id: I1b5d7c2452be1b9e4d659caf8278e0e16aa67156
Reviewed-on: https://gerrit.chromium.org/gerrit/38786
Commit-Ready: Tan Gao <tgao@chromium.org>
Reviewed-by: Tan Gao <tgao@chromium.org>
Tested-by: Tan Gao <tgao@chromium.org>
3 files changed