Passes toolstash -cmp.

Change-Id: I4bd60f7ebba5457e7b3ece688fee2351bfeeb59a
Reviewed-on: https://go-review.googlesource.com/37874
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alessandro Arzilli <alessandro.arzilli@gmail.com>
Reviewed-by: Than McIntosh <thanm@google.com>