UPSTREAM: Fix a crash when using clientid's.

(cherry picked from commit 6624d6bbc1a379bb8338390938a387e22283397b)

BUG=chromium:215026
TEST=(TODO: Use DHCP autotests)

Change-Id: Ib8099fb0f934dd5f0f59e0f4f86c8695cd5a7818
Reviewed-on: https://gerrit.chromium.org/gerrit/31726
Commit-Queue: Paul Stewart <pstew@chromium.org>
Reviewed-by: Paul Stewart <pstew@chromium.org>
Tested-by: Paul Stewart <pstew@chromium.org>
1 file changed