QUIC - Add back to code to experiment with delay_tcp_race. By default,

net/quic/quic_stream_factory.cc

 // Copyright (c) 2012 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_stream_factory.h"
 
 #include <algorithm>
 #include <tuple>
 #include <utility>
 
@@ skipping 569 matching lines @@
     bool enable_connection_racing,
     bool enable_non_blocking_io,
     bool disable_disk_cache,
     bool prefer_aes,
     int max_number_of_lossy_connections,
     float packet_loss_threshold,
     int max_disabled_reasons,
     int threshold_public_resets_post_handshake,
     int threshold_timeouts_with_open_streams,
     int socket_receive_buffer_size,
+    bool delay_tcp_race,
     int max_server_configs_stored_in_properties,
     bool close_sessions_on_ip_change,
     bool disable_quic_on_timeout_with_open_streams,
     int idle_connection_timeout_seconds,
     bool migrate_sessions_on_network_change,
     bool migrate_sessions_early,
     const QuicTagVector& connection_options,
     bool enable_token_binding)
     : require_confirmation_(true),
       host_resolver_(host_resolver),
@@ skipping 28 matching lines @@
       max_disabled_reasons_(max_disabled_reasons),
       num_public_resets_post_handshake_(0),
       num_timeouts_with_open_streams_(0),
       max_public_resets_post_handshake_(0),
       max_timeouts_with_open_streams_(0),
       threshold_timeouts_with_open_streams_(
           threshold_timeouts_with_open_streams),
       threshold_public_resets_post_handshake_(
           threshold_public_resets_post_handshake),
       socket_receive_buffer_size_(socket_receive_buffer_size),
+      delay_tcp_race_(delay_tcp_race),
       yield_after_packets_(kQuicYieldAfterPacketsRead),
       yield_after_duration_(QuicTime::Delta::FromMilliseconds(
           kQuicYieldAfterDurationMilliseconds)),
       close_sessions_on_ip_change_(close_sessions_on_ip_change),
       migrate_sessions_on_network_change_(
           migrate_sessions_on_network_change &&
           NetworkChangeNotifier::AreNetworkHandlesSupported()),
       migrate_sessions_early_(migrate_sessions_early &&
                               migrate_sessions_on_network_change_),
       port_seed_(random_generator_->RandUint64()),
@@ skipping 76 matching lines @@
                                              local_address_.address());
   }
 }
 
 bool QuicStreamFactory::ZeroRTTEnabledFor(const QuicServerId& quic_server_id) {
   return !(require_confirmation_ || CryptoConfigCacheIsEmpty(quic_server_id));
 }
 
 base::TimeDelta QuicStreamFactory::GetTimeDelayForWaitingJob(
     const QuicServerId& server_id) {
-  if (require_confirmation_)
+  if (!delay_tcp_race_ || require_confirmation_)
     return base::TimeDelta();
   int64_t srtt =
       1.5 * GetServerNetworkStatsSmoothedRttInMicroseconds(server_id);
   // Picked 300ms based on mean time from
   // Net.QuicSession.HostResolution.HandshakeConfirmedTime histogram.
   const int kDefaultRTT = 300 * kNumMicrosPerMilli;
   if (!srtt)
     srtt = kDefaultRTT;
   return base::TimeDelta::FromMicroseconds(srtt);
 }
@@ skipping 1042 matching lines @@
   // Since the session was active, there's no longer an
   // HttpStreamFactoryImpl::Job running which can mark it broken, unless the TCP
   // job also fails. So to avoid not using QUIC when we otherwise could, we mark
   // it as recently broken, which means that 0-RTT will be disabled but we'll
   // still race.
   http_server_properties_->MarkAlternativeServiceRecentlyBroken(
       alternative_service);
 }
 
 }  // namespace net