Updates #22687.

Change-Id: Iedccd9d2416ae7150cd2febe81c8bc9493d8d65c
Reviewed-on: https://go-review.googlesource.com/112915
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>