Oilpan: fix build after r183736.

TBR=haraken,oilpan-reviews
BUG=397902
NOTRY=true

Review URL: https://codereview.chromium.org/656093002

git-svn-id: svn://svn.chromium.org/blink/trunk@183740 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Oilpan: fix build after r183735.

TBR=haraken,oilpan-reviews
BUG=421948
NOTRY=true

Review URL: https://codereview.chromium.org/655213002

git-svn-id: svn://svn.chromium.org/blink/trunk@183741 bbb929c8-8fbe-4397-9dbb-9b2b20218538