Fix oilpan build after service worker changes.

TBR=dominicc@chromium.org, haraken@chromium.org

Review URL: https://codereview.chromium.org/393103005

git-svn-id: svn://svn.chromium.org/blink/trunk@178258 bbb929c8-8fbe-4397-9dbb-9b2b20218538