Fix an UAF in the unittests.
Fix an UAF in the unittests.

BUG=
R=chrisha@chromium.org

Review URL: https://codereview.chromium.org/1378643002 .

google/syzygy,google/syzygy,google/syzygy,Eloston/syzygy,Eloston/syzygy,google/syzygy,supriyantomaftuh/syzygy,supriyantomaftuh/syzygy,supriyantomaftuh/syzygy,supriyantomaftuh/syzygy