Use a field trial to decide if QUIC should attempt to prevent packet fragmentation.

net/quic/chromium/quic_stream_factory.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.
 
 #ifndef NET_QUIC_QUIC_STREAM_FACTORY_H_
 #define NET_QUIC_QUIC_STREAM_FACTORY_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 178 matching lines @@
       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,
       int packet_reader_yield_after_duration_milliseconds,
       bool migrate_sessions_on_network_change,
       bool migrate_sessions_early,
       bool allow_server_migration,
       bool force_hol_blocking,
       bool race_cert_verification,
+      bool quic_do_not_fragment,
       const QuicTagVector& connection_options,
       bool enable_token_binding);
   ~QuicStreamFactory() override;
 
   // Returns true if there is an existing session for |server_id| or if the
   // request can be pooled to an existing session to the IP address of
   // |destination|.
   bool CanUseExistingSession(const QuicServerId& server_id,
                              const HostPortPair& destination);
 
@@ skipping 407 matching lines @@
   // If set, allows migration of connection to server-specified alternate
   // server address.
   const bool allow_server_migration_;
 
   // If set, force HOL blocking.  For measurement purposes.
   const bool force_hol_blocking_;
 
   // Set if cert verification is to be raced with host resolution.
   bool race_cert_verification_;
 
+  // If set, configure QUIC sockets to not fragment packets.
+  bool quic_do_not_fragment_;
+
   // Each profile will (probably) have a unique port_seed_ value.  This value
   // is used to help seed a pseudo-random number generator (PortSuggester) so
   // that we consistently (within this profile) suggest the same ephemeral
   // port when we re-connect to any given server/port.  The differences between
   // profiles (probablistically) prevent two profiles from colliding in their
   // ephemeral port requests.
   uint64_t port_seed_;
 
   // Local address of socket that was created in CreateSession.
   IPEndPoint local_address_;
@@ skipping 15 matching lines @@
   const scoped_refptr<SSLConfigService> ssl_config_service_;
 
   base::WeakPtrFactory<QuicStreamFactory> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicStreamFactory);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_STREAM_FACTORY_H_