Add support for MD2, MD4, and MD5 to SignatureAlgorithm.

net/cert/internal/signature_algorithm.h

 // Copyright 2015 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_CERT_INTERNAL_SIGNATURE_ALGORITHM_H_
 #define NET_CERT_INTERNAL_SIGNATURE_ALGORITHM_H_
 
 #include <stdint.h>
 
 #include <memory>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "net/base/net_export.h"
 
 namespace net {
 
 class CertErrors;
 
 namespace der {
 class Input;
 }  // namespace der
 
 // The digest algorithm used within a signature.
 enum class DigestAlgorithm {
+  Md2,
+  Md4,
+  Md5,
   Sha1,
   Sha256,
   Sha384,
   Sha512,
 };
 
 // The signature scheme used within a signature. Parameters are specified
 // separately.
 enum class SignatureAlgorithmId {
   RsaPkcs1,  // RSA PKCS#1 v1.5
@@ skipping 87 matching lines @@
   const SignatureAlgorithmId algorithm_;
   const DigestAlgorithm digest_;
   const std::unique_ptr<SignatureAlgorithmParameters> params_;
 
   DISALLOW_COPY_AND_ASSIGN(SignatureAlgorithm);
 };
 
 }  // namespace net
 
 #endif  // NET_CERT_INTERNAL_SIGNATURE_ALGORITHM_H_