Add ChaCha20Poly1305Encrypter, based on

net/quic/crypto/crypto_protocol.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_CRYPTO_CRYPTO_PROTOCOL_H_
 #define NET_QUIC_CRYPTO_CRYPTO_PROTOCOL_H_
 
 #include <string>
 
 #include "net/base/net_export.h"
@@ skipping 22 matching lines @@
                                                 // pairs
 const QuicTag kPRST = TAG('P', 'R', 'S', 'T');  // Public reset
 
 // Key exchange methods
 const QuicTag kP256 = TAG('P', '2', '5', '6');  // ECDH, Curve P-256
 const QuicTag kC255 = TAG('C', '2', '5', '5');  // ECDH, Curve25519
 
 // AEAD algorithms
 const QuicTag kNULL = TAG('N', 'U', 'L', 'N');  // null algorithm
 const QuicTag kAESG = TAG('A', 'E', 'S', 'G');  // AES128 + GCM-12
+const QuicTag kCC12 = TAG('C', 'C', '1', '2');  // ChaCha20 + Poly1305
 
 // Congestion control feedback types
 const QuicTag kQBIC = TAG('Q', 'B', 'I', 'C');  // TCP cubic
 const QuicTag kPACE = TAG('P', 'A', 'C', 'E');  // Paced TCP cubic
 const QuicTag kINAR = TAG('I', 'N', 'A', 'R');  // Inter arrival
 
 // Proof types (i.e. certificate types)
 // NOTE: although it would be silly to do so, specifying both kX509 and kX59R
 // is allowed and is equivalent to specifying only kX509.
 const QuicTag kX509 = TAG('X', '5', '0', '9');  // X.509 certificate, all key
@@ skipping 81 matching lines @@
 // amplification factor of any mirror DoS attack.
 //
 // A client may pad an inchoate client hello to a size larger than
 // kClientHelloMinimumSize to make it more likely to receive a complete
 // rejection message.
 const size_t kClientHelloMinimumSize = 1024;
 
 }  // namespace net
 
 #endif  // NET_QUIC_CRYPTO_CRYPTO_PROTOCOL_H_