Adds an internal server and chromium's flag for disabling/enabling FEC

net/quic/quic_server_session.cc

Index: net/quic/quic_server_session.cc
diff --git a/net/quic/quic_server_session.cc b/net/quic/quic_server_session.cc
index 1de91a44aa1ec10da4a1aadba11cbdcfc9396d79..b9acb2239558f17559227cf0576a71eec6d9f8de 100644
--- a/net/quic/quic_server_session.cc
+++ b/net/quic/quic_server_session.cc
@@ -6,6 +6,7 @@
 
 #include "base/logging.h"
 #include "net/quic/quic_connection.h"
+#include "net/quic/quic_flags.h"
 #include "net/quic/quic_spdy_server_stream.h"
 #include "net/quic/reliable_quic_stream.h"
 
@@ -29,6 +30,18 @@ QuicCryptoServerStream* QuicServerSession::CreateQuicCryptoServerStream(
   return new QuicCryptoServerStream(crypto_config, this);
 }
 
+void QuicServerSession::OnConfigNegotiated() {
+  QuicSession::OnConfigNegotiated();
+  if (!FLAGS_enable_quic_fec ||
+      !config()->HasReceivedConnectionOptions() ||
+      !ContainsQuicTag(config()->ReceivedConnectionOptions(), kFHDR)) {
+    return;
+  }
+  // kFHDR config maps to FEC protection always for headers stream.
+  // TODO(jri): Add crypto stream in addition to headers for kHDR.
+  headers_stream_->set_fec_policy(FEC_PROTECT_ALWAYS);
+}
+
 void QuicServerSession::OnConnectionClosed(QuicErrorCode error,
                                            bool from_peer) {
   QuicSession::OnConnectionClosed(error, from_peer);