Add a merely pass-through QuicMultipathSentPacketManager. Protected behind blocked flag FLAGS_quic_…

net/quic/quic_connection.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_connection.h"
 
 #include <string.h>
 #include <sys/types.h>
 
 #include <algorithm>
@@ skipping 300 matching lines @@
       largest_received_packet_size_(0),
       goaway_sent_(false),
       goaway_received_(false),
       multipath_enabled_(false) {
   DVLOG(1) << ENDPOINT
            << "Created connection with connection_id: " << connection_id;
   framer_.set_visitor(this);
   framer_.set_received_entropy_calculator(&received_packet_manager_);
   last_stop_waiting_frame_.least_unacked = 0;
   stats_.connection_creation_time = clock_->ApproximateNow();
+  if (FLAGS_quic_enable_multipath) {
+    sent_packet_manager_.reset(new QuicMultipathSentPacketManager(
+        sent_packet_manager_.release(), this));
+  }
   // TODO(ianswett): Supply the NetworkChangeVisitor as a constructor argument
   // and make it required non-null, because it's always used.
   sent_packet_manager_->SetNetworkChangeVisitor(this);
   // Allow the packet writer to potentially reduce the packet size to a value
   // even smaller than kDefaultMaxPacketSize.
   SetMaxPacketLength(perspective_ == Perspective::IS_SERVER
                          ? kDefaultServerMaxPacketSize
                          : kDefaultMaxPacketSize);
   received_packet_manager_.SetVersion(version());
 }
@@ skipping 2178 matching lines @@
 // the sender and a signaling mechanism -- if the sender uses a
 // different MinRTO, we may get spurious retransmissions. May not have
 // any benefits, but if the delayed ack becomes a significant source
 // of (likely, tail) latency, then consider such a mechanism.
 const QuicTime::Delta QuicConnection::DelayedAckTime() {
   return QuicTime::Delta::FromMilliseconds(
       min(kMaxDelayedAckTimeMs, kMinRetransmissionTimeMs / 2));
 }
 
 }  // namespace net