Remove the deprecated cipher fallback.

net/ssl/ssl_config.h

Index: net/ssl/ssl_config.h
diff --git a/net/ssl/ssl_config.h b/net/ssl/ssl_config.h
index eee5622744c9c204950d96783f167b8280939d74..cb3a233394e8babf361a15002f968d7fed7c7059 100644
--- a/net/ssl/ssl_config.h
+++ b/net/ssl/ssl_config.h
@@ -101,19 +101,6 @@ struct NET_EXPORT SSLConfig {
   // 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