Make CookieMonster::Delegate top-level and remove global CookieMonster::EnableFileScheme().

Relanding parts of https://chromiumcodereview.appspot.com/12546016

R=rsleevi@chromium.org
TBR=jam
BUG=159193,331424

Review URL: https://codereview.chromium.org/93593005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242913 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 242913