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
  void RevokeScheme(const std::string& scheme) {
    scheme_policy_[scheme] = false;
  }

  void RevokeScheme(const std::string& scheme) {
    scheme_policy_[scheme] = false;
  }
