WorkerMain contains code to initialize the sandbox on OS X which is disabled due to a typo. The sandbox is in fact enabled in ContentMainImpl::Initialize.

      This CL removes the redundant code and adds a CHECK() to ensure that the sandbox has already been initialized.

Bug=None

Review URL: https://chromiumcodereview.appspot.com/12820006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@188209 0039d316-1c4b-4281-b951-d872f2087c98