Generated by eg, manually fixed up.

I’m not thrilled about having a setter,
but given the variety of contexts in which this
gets fiddled with, it is the cleanest
available alternative.

Change-Id: Ibdf23e638fe0bdabded014c9e59d557fab8c955f
Reviewed-on: https://go-review.googlesource.com/21341Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>