message: Disable SCTP asconf and auth extensions.
  WebRTC doesn't use these features, so disable them to reduce the
  potential attack surface.
  Cr-Commit-Position: refs/heads/master@{#31540}
diff: @@ -269,6 +269,11 @@ class SctpTransport::UsrSctpWrapper {
  // TODO(ldixon): Consider turning this on/off.
  usrsctp_sysctl_set_sctp_ecn_enable(0);
  + // WebRTC doesn't use these features, so disable them to reduce the
  + // potential attack surface.
  + usrsctp_sysctl_set_sctp_asconf_enable(0);
  + usrsctp_sysctl_set_sctp_auth_enable(0);
  +
  // This is harmless, but we should find out when the library default
  // changes.
  int send_size = usrsctp_sysctl_get_sctp_sendspace();
  