[refactor] Extract the CertVerifyResult assignment of has_md2, has_md4,

net/cert/x509_certificate_nss.cc

Index: net/cert/x509_certificate_nss.cc
diff --git a/net/cert/x509_certificate_nss.cc b/net/cert/x509_certificate_nss.cc
index abb6f20462e3113a198298359a031ddeb2aeb5cd..d03277906e907d34e54d244e6f2f18b139ac2083 100644
--- a/net/cert/x509_certificate_nss.cc
+++ b/net/cert/x509_certificate_nss.cc
@@ -263,6 +263,28 @@ void X509Certificate::GetPublicKeyInfo(OSCertHandle cert_handle,
 }
 
 // static
+X509Certificate::SignatureHashAlgorithm
+X509Certificate::GetSignatureHashAlgorithm(OSCertHandle cert_handle) {
+  SECAlgorithmID& signature = cert_handle->signature;
+  SECOidTag oid_tag = SECOID_FindOIDTag(&signature.algorithm);
+  switch (oid_tag) {
+    case SEC_OID_PKCS1_MD5_WITH_RSA_ENCRYPTION:
+      return kSignatureHashAlgorithmMd5;
+    case SEC_OID_PKCS1_MD2_WITH_RSA_ENCRYPTION:
+      return kSignatureHashAlgorithmMd2;
+    case SEC_OID_PKCS1_MD4_WITH_RSA_ENCRYPTION:
+      return kSignatureHashAlgorithmMd4;
+    case SEC_OID_PKCS1_SHA1_WITH_RSA_ENCRYPTION:
+    case SEC_OID_ISO_SHA1_WITH_RSA_SIGNATURE:
+    case SEC_OID_ANSIX9_DSA_SIGNATURE_WITH_SHA1_DIGEST:
+    case SEC_OID_ANSIX962_ECDSA_SHA1_SIGNATURE:
+      return kSignatureHashAlgorithmSha1;
+    default:
+      return kSignatureHashAlgorithmOther;
+  }
+}
+
+// static
 bool X509Certificate::IsSelfSigned(OSCertHandle cert_handle) {
   crypto::ScopedSECKEYPublicKey public_key(CERT_ExtractPublicKey(cert_handle));
   if (!public_key.get())