Remove multipath_enabled from quic_config and quic_connection. No functional change expected.

net/quic/core/quic_packet_creator.h

 // 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.
 //
 // Accumulates frames for the next packet until more frames no longer fit or
-// it's time to create a packet from them. If multipath enabled, only creates
-// packets on one path at the same time. Currently, next packet number is
-// tracked per-path.
+// it's time to create a packet from them.
 
 #ifndef NET_QUIC_CORE_QUIC_PACKET_CREATOR_H_
 #define NET_QUIC_CORE_QUIC_PACKET_CREATOR_H_
 
 #include <cstddef>
 #include <memory>
 #include <string>
 #include <unordered_map>
 #include <utility>
 #include <vector>
@@ skipping 285 matching lines @@
 
   // The latched value of FLAGS_quic_reloadable_flag_quic_no_stop_waiting_frames
   bool latched_flag_no_stop_waiting_frames_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicPacketCreator);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_CORE_QUIC_PACKET_CREATOR_H_