Remove the deprecated cipher fallback.

net/ssl/ssl_config.h

 // Copyright 2014 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_SSL_SSL_CONFIG_H_
 #define NET_SSL_SSL_CONFIG_H_
 
 #include <stdint.h>
 
 #include "base/memory/ref_counted.h"
@@ skipping 83 matching lines @@
   // Presorted list of cipher suites which should be explicitly prevented from
   // being used in addition to those disabled by the net built-in policy.
   //
   // Though cipher suites are sent in TLS as "uint8_t CipherSuite[2]", in
   // big-endian form, they should be declared in host byte order, with the
   // first uint8_t occupying the most significant byte.
   // Ex: To disable TLS_RSA_WITH_RC4_128_MD5, specify 0x0004, while to
   // disable TLS_ECDH_ECDSA_WITH_RC4_128_SHA, specify 0xC002.
   std::vector<uint16_t> disabled_cipher_suites;
 
-  // Enables deprecated cipher suites. These cipher suites are selected under a
-  // fallback to distinguish servers which require them from servers which
-  // merely prefer them.
-  //
-  // NOTE: because they are under a fallback, connections are still vulnerable
-  // to them as far as downgrades are concerned, so this should only be used for
-  // measurement of ciphers not to be carried long-term. It is no fix for
-  // servers with bad configurations without full removal.
-  //
-  // TODO(davidben): This is no longer used. Remove
-  // it. https://crbug.com/684730.
-  bool deprecated_cipher_suites_enabled;
-
   // Enables the version interference probing mode. While TLS 1.3 has avoided
   // most endpoint intolerance, middlebox interference with TLS 1.3 is
   // rampant. This causes the connection to be discarded on success with
   // ERR_SSL_VERSION_INTERFERENCE.
   bool version_interference_probe;
 
   bool channel_id_enabled;   // True if TLS channel ID extension is enabled.
 
   // List of Token Binding key parameters supported by the client. If empty,
   // Token Binding will be disabled, even if token_binding_enabled is true.
@@ skipping 50 matching lines @@
   // The list of application-level protocols to enable renegotiation for.
   NextProtoVector renego_allowed_for_protos;
 
   scoped_refptr<X509Certificate> client_cert;
   scoped_refptr<SSLPrivateKey> client_private_key;
 };
 
 }  // namespace net
 
 #endif  // NET_SSL_SSL_CONFIG_H_