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

net/http/http_network_session.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_HTTP_HTTP_NETWORK_SESSION_H_
 #define NET_HTTP_HTTP_NETWORK_SESSION_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 168 matching lines @@
     bool quic_migrate_sessions_early;
     // If true, allows migration of QUIC connections to a server-specified
     // alternate server address.
     bool quic_allow_server_migration;
     // If true, bidirectional streams over QUIC will be disabled.
     bool quic_disable_bidirectional_streams;
     // If true, enable force HOL blocking.  For measurement purposes.
     bool quic_force_hol_blocking;
     // If true, race cert verification with host resolution.
     bool quic_race_cert_verification;
+    // If true, configure QUIC sockets to not fragment packets.
+    bool quic_do_not_fragment;
 
     ProxyDelegate* proxy_delegate;
     // Enable support for Token Binding.
     bool enable_token_binding;
   };
 
   enum SocketPoolType {
     NORMAL_SOCKET_POOL,
     WEBSOCKET_SOCKET_POOL,
     NUM_SOCKET_POOL_TYPES
@@ skipping 106 matching lines @@
   bool enabled_protocols_[NUM_VALID_ALTERNATE_PROTOCOLS];
 
   Params params_;
 
   std::unique_ptr<base::MemoryPressureListener> memory_pressure_listener_;
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP_HTTP_NETWORK_SESSION_H_