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

net/cert/x509_certificate.h

Index: net/cert/x509_certificate.h
diff --git a/net/cert/x509_certificate.h b/net/cert/x509_certificate.h
index 613bd09509004301c7d4f4e72d6704733df5c717..138192c7c1c9aa560e80821d3b4989541d52ed13 100644
--- a/net/cert/x509_certificate.h
+++ b/net/cert/x509_certificate.h
@@ -80,6 +80,14 @@ class NET_EXPORT X509Certificate
     kPublicKeyTypeECDH
   };
 
+  enum SignatureHashAlgorithm {
+    kSignatureHashAlgorithmMd2,
+    kSignatureHashAlgorithmMd4,
+    kSignatureHashAlgorithmMd5,
+    kSignatureHashAlgorithmSha1,
+    kSignatureHashAlgorithmOther,
+  };
+
   enum Format {
     // The data contains a single DER-encoded certificate, or a PEM-encoded
     // DER certificate with the PEM encoding block name of "CERTIFICATE".
@@ -327,6 +335,15 @@ class NET_EXPORT X509Certificate
                                size_t* size_bits,
                                PublicKeyType* type);
 
+  // Returns the digest algorithm used in |cert_handle|'s signature.
+  // If the digest algorithm cannot be determined, or if it is not one
+  // of the explicitly enumerated values, kSignatureHashAlgorithmOther
+  // will be returned.
+  // NOTE: No validation of the signature is performed, and thus invalid
+  // signatures may result in seemingly meaningful values.
+  static SignatureHashAlgorithm GetSignatureHashAlgorithm(
+      OSCertHandle cert_handle);
+
   // Returns the OSCertHandle of this object. Because of caching, this may
   // differ from the OSCertHandle originally supplied during initialization.
   // Note: On Windows, CryptoAPI may return unexpected results if this handle