autotest: Add logic to log netperf results as keyvals

Write a delegate object that knows how to log netperf results as
keyvals.  This allows us to reuse the same logging format between tests.

BUG=chromium:279395
TEST=A test consuming this logic runs successfully.

Change-Id: I7bf64f3f9fa1771c5faa14315036056d81ae837d
Reviewed-on: https://chromium-review.googlesource.com/66973
Reviewed-by: Christopher Wiley <wiley@chromium.org>
Tested-by: Christopher Wiley <wiley@chromium.org>
Commit-Queue: Christopher Wiley <wiley@chromium.org>
1 file changed