SpdySession currently saves Quic alternative service to HttpServerProperties without checking whether the Quic version advertised by the server is supported by the client. This will lead us to create unnecessary QUIC connections if the version is actually not supported. 

Additionally, HttpStreamFactory::ProcessAlternativeService() does the version check, we should probably consider factory parsing into a single function that could be used in both places.

void SpdySession::OnAltSvc(...) {
  ...

  for (const SpdyAltSvcWireFormat::AlternativeService& altsvc : altsvc_vector) {
    const NextProto protocol = NextProtoFromString(altsvc.protocol_id);
    if (protocol == kProtoUnknown)
      continue;
    const AlternativeService alternative_service(protocol, altsvc.host,
                                                 altsvc.port);
    const base::Time expiration =
        now + base::TimeDelta::FromSeconds(altsvc.max_age);
    alternative_service_info_vector.push_back(                       <------ no filtering on version field
        AlternativeServiceInfo(alternative_service, expiration));
  }
  http_server_properties_->SetAlternativeServices(
      scheme_host_port, alternative_service_info_vector);

  ...
}