New versions understand CIPD_PROTOCOL=v2.

R=tandrii@chromium.org
BUG=801423

Change-Id: I6ca28638393957a9965a0ded7ed49c15b3a8f5b0
Reviewed-on: https://chromium-review.googlesource.com/1114296Reviewed-by: Robbie Iannucci <iannucci@chromium.org>
Commit-Queue: Vadim Shtayura <vadimsh@chromium.org>