Oilpan: build fix after r172864.

R=haraken@chromium.org
BUG=363569
NOTRY=true

Review URL: https://codereview.chromium.org/260453002

git-svn-id: svn://svn.chromium.org/blink/trunk@172870 bbb929c8-8fbe-4397-9dbb-9b2b20218538