Found by github.com/mvdan/unparam.

Change-Id: I20145440ff1bcd27fcf15a740354c52f313e536c
Reviewed-on: https://go-review.googlesource.com/37894
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>