Add path_id to SerializedPacket. No functional change.

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 1711 matching lines @@
 }
 
 void QuicConnection::OnWriteError(int error_code) {
   DVLOG(1) << ENDPOINT << "Write failed with error: " << error_code
            << " (" << ErrorToString(error_code) << ")";
   // We can't send an error as the socket is presumably borked.
   CloseConnection(QUIC_PACKET_WRITE_ERROR, false);
 }
 
 void QuicConnection::OnSerializedPacket(SerializedPacket* serialized_packet) {
+  DCHECK_NE(kInvalidPathId, serialized_packet->path_id);
   if (serialized_packet->packet == nullptr) {
     // We failed to serialize the packet, so close the connection.
     // CloseConnection does not send close packet, so no infinite loop here.
     CloseConnection(QUIC_ENCRYPTION_FAILURE, false);
     return;
   }
   if (serialized_packet->is_fec_packet && fec_alarm_->IsSet()) {
     // If an FEC packet is serialized with the FEC alarm set, cancel the alarm.
     fec_alarm_->Cancel();
   }
@@ skipping 661 matching lines @@
   SendMtuDiscoveryPacket(mtu_discovery_target_);
 
   DCHECK(!mtu_discovery_alarm_->IsSet());
 }
 
 bool QuicConnection::ack_frame_updated() const {
   return received_packet_manager_.ack_frame_updated();
 }
 
 }  // namespace net