Add ChaCha20Poly1305Encrypter, based on

net/quic/crypto/aes_128_gcm_12_decrypter.h

Index: net/quic/crypto/aes_128_gcm_12_decrypter.h
===================================================================
--- net/quic/crypto/aes_128_gcm_12_decrypter.h	(revision 255481)
+++ net/quic/crypto/aes_128_gcm_12_decrypter.h	(working copy)
@@ -5,28 +5,17 @@
 #ifndef NET_QUIC_CRYPTO_AES_128_GCM_12_DECRYPTER_H_
 #define NET_QUIC_CRYPTO_AES_128_GCM_12_DECRYPTER_H_
 
-#include <string>
+#include "net/quic/crypto/aead_base_decrypter.h"
 
-#include "base/compiler_specific.h"
-#include "net/quic/crypto/quic_decrypter.h"
-
-#if defined(USE_OPENSSL)
-#include "net/quic/crypto/scoped_evp_aead_ctx.h"
-#endif
-
 namespace net {
 
-namespace test {
-class Aes128Gcm12DecrypterPeer;
-}  // namespace test
-
 // An Aes128Gcm12Decrypter is a QuicDecrypter that implements the
 // AEAD_AES_128_GCM_12 algorithm specified in RFC 5282. Create an instance by
 // calling QuicDecrypter::Create(kAESG).
 //
 // It uses an authentication tag of 12 bytes (96 bits). The fixed prefix
 // of the nonce is four bytes.
-class NET_EXPORT_PRIVATE Aes128Gcm12Decrypter : public QuicDecrypter {
+class NET_EXPORT_PRIVATE Aes128Gcm12Decrypter : public AeadBaseDecrypter {
  public:
   enum {
     // Authentication tags are truncated to 96 bits.
@@ -36,31 +25,13 @@
   Aes128Gcm12Decrypter();
   virtual ~Aes128Gcm12Decrypter();
 
-  // Returns true if the underlying crypto library supports AES GCM.
-  static bool IsSupported();
-
-  // QuicDecrypter implementation
-  virtual bool SetKey(base::StringPiece key) OVERRIDE;
-  virtual bool SetNoncePrefix(base::StringPiece nonce_prefix) OVERRIDE;
-  virtual bool Decrypt(base::StringPiece nonce,
-                       base::StringPiece associated_data,
-                       base::StringPiece ciphertext,
-                       unsigned char* output,
-                       size_t* output_length) OVERRIDE;
-  virtual QuicData* DecryptPacket(QuicPacketSequenceNumber sequence_number,
-                                  base::StringPiece associated_data,
-                                  base::StringPiece ciphertext) OVERRIDE;
-  virtual base::StringPiece GetKey() const OVERRIDE;
-  virtual base::StringPiece GetNoncePrefix() const OVERRIDE;
-
- private:
-  // The 128-bit AES key.
-  unsigned char key_[16];
-  // The nonce prefix.
-  unsigned char nonce_prefix_[4];
-
-#if defined(USE_OPENSSL)
-  ScopedEVPAEADCtx ctx_;
+#if !defined(USE_OPENSSL)
+ protected:
+  // AeadBaseDecrypter methods:
+  virtual void FillAeadParams(base::StringPiece nonce,
+                              base::StringPiece associated_data,
+                              size_t auth_tag_size,
+                              AeadParams* aead_params) const OVERRIDE;
 #endif
 };