Update several clang warnings after r287092.

BUG=none
R=hans@chromium.org
TBR=eseidel

Review URL: https://codereview.chromium.org/436993002

git-svn-id: svn://svn.chromium.org/blink/trunk@179429 bbb929c8-8fbe-4397-9dbb-9b2b20218538