Update from https://crrev.com/312398

net/quic/quic_config.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/quic_config.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "net/quic/crypto/crypto_handshake_message.h"
@@ skipping 410 matching lines @@
       *error_details = "Bad " + QuicUtils::TagToString(tag_);
       break;
   }
   return error;
 }
 
 QuicConfig::QuicConfig()
     : max_time_before_crypto_handshake_(QuicTime::Delta::Zero()),
       max_idle_time_before_crypto_handshake_(QuicTime::Delta::Zero()),
       max_undecryptable_packets_(0),
-      congestion_feedback_(kCGST, PRESENCE_REQUIRED),
+      congestion_feedback_(kCGST, PRESENCE_OPTIONAL),
       connection_options_(kCOPT, PRESENCE_OPTIONAL),
       idle_connection_state_lifetime_seconds_(kICSL, PRESENCE_REQUIRED),
       silent_close_(kSCLS, PRESENCE_OPTIONAL),
       max_streams_per_connection_(kMSPC, PRESENCE_REQUIRED),
       bytes_for_connection_id_(kTCID, PRESENCE_OPTIONAL),
       initial_round_trip_time_us_(kIRTT, PRESENCE_OPTIONAL),
       initial_stream_flow_control_window_bytes_(kSFCW, PRESENCE_OPTIONAL),
       initial_session_flow_control_window_bytes_(kCFCW, PRESENCE_OPTIONAL),
       socket_receive_buffer_(kSRBF, PRESENCE_OPTIONAL) {
   SetDefaults();
 }
 
 QuicConfig::~QuicConfig() {}
 
-void QuicConfig::SetCongestionFeedback(
-    const QuicTagVector& congestion_feedback,
-    QuicTag default_congestion_feedback) {
-  congestion_feedback_.set(congestion_feedback, default_congestion_feedback);
-}
-
-QuicTag QuicConfig::CongestionFeedback() const {
-  return congestion_feedback_.GetTag();
-}
-
 void QuicConfig::SetConnectionOptionsToSend(
     const QuicTagVector& connection_options) {
   connection_options_.SetSendValues(connection_options);
 }
 
 bool QuicConfig::HasReceivedConnectionOptions() const {
   return connection_options_.HasReceivedValues();
 }
 
 QuicTagVector QuicConfig::ReceivedConnectionOptions() const {
@@ skipping 138 matching lines @@
   // TODO(ianswett): Add the negotiated parameters once and iterate over all
   // of them in negotiated, ToHandshakeMessage, ProcessClientHello, and
   // ProcessServerHello.
   return congestion_feedback_.negotiated() &&
       idle_connection_state_lifetime_seconds_.negotiated() &&
       max_streams_per_connection_.negotiated();
 }
 
 void QuicConfig::SetDefaults() {
   QuicTagVector congestion_feedback;
+  // TODO(alyssar) stop sending this once QUIC_VERSION_23 is sunset.
+  // This field was required until version 22 was removed but by the time
+  // QUIC_VERSION_23 is sunset, no users of QUIC_VERSION_24 should be expecting
+  // it.
   congestion_feedback.push_back(kQBIC);
   congestion_feedback_.set(congestion_feedback, kQBIC);
   idle_connection_state_lifetime_seconds_.set(kMaximumIdleTimeoutSecs,
                                               kDefaultIdleTimeoutSecs);
   if (FLAGS_quic_allow_silent_close) {
     silent_close_.set(1, 0);
   } else {
     silent_close_.set(0, 0);
   }
   SetMaxStreamsPerConnection(kDefaultMaxStreamsPerConnection,
@@ skipping 65 matching lines @@
         peer_hello, hello_type, error_details);
   }
   if (error == QUIC_NO_ERROR) {
     error = connection_options_.ProcessPeerHello(
         peer_hello, hello_type, error_details);
   }
   return error;
 }
 
 }  // namespace net