Avoid excessive nesting / recursion in browser URL handling.

BUG=31517
TEST=ChildProcessSecurityPolicyTest

Review URL: http://codereview.chromium.org/525038

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@35585 0039d316-1c4b-4281-b951-d872f2087c98
  ~SecurityState() {
    scheme_policy_.clear();
  }

  ~SecurityState() {
    scheme_policy_.clear();
  }
