Fail QUIC TLS handshake for mTLS domains.

Protected by FLAGS_quic_reloadable_flag_quic_fail_handshake_for_mtls_domains.

PiperOrigin-RevId: 343851196
Change-Id: I22c59526bf62982342b33faaeb95d38df85dbaf0

quic/core/tls_server_handshaker.h

diff --git a/quic/core/tls_server_handshaker.h b/quic/core/tls_server_handshaker.h
index 09d03eb..7334cd9 100644
--- a/quic/core/tls_server_handshaker.h
+++ b/quic/core/tls_server_handshaker.h
@@ -79,6 +79,8 @@
   // before we generate transport parameters.
   virtual void OverrideQuicConfigDefaults(QuicConfig* config);
 
+  virtual bool ValidateHostname(const std::string& hostname) const;
+
   const TlsConnection* tls_connection() const override {
     return &tls_connection_;
   }
@@ -159,7 +161,6 @@
     TlsServerHandshaker* handshaker_;
   };
 
-  virtual bool ValidateHostname(const std::string& hostname) const;
   bool SetTransportParameters();
   bool ProcessTransportParameters(const SSL_CLIENT_HELLO* client_hello,
                                   std::string* error_details);