Add 'default:' case to fix findbugs warning.

NOTRY=true

Review URL: https://codereview.chromium.org/133263003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244531 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 244531