Update from chromium https://crrev.com/302282

net/cert/x509_certificate_mac.cc

 // 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.
 
 #include "net/cert/x509_certificate.h"
 
 #include <CommonCrypto/CommonDigest.h>
 #include <CoreServices/CoreServices.h>
 #include <Security/Security.h>
 
@@ skipping 513 matching lines @@
     case CSSM_ALGID_DH:
       *type = kPublicKeyTypeDH;
       break;
     default:
       *type = kPublicKeyTypeUnknown;
       *size_bits = 0;
       break;
   }
 }
 
+// static
+bool X509Certificate::IsSelfSigned(OSCertHandle cert_handle) {
+  x509_util::CSSMCachedCertificate cached_cert;
+  OSStatus status = cached_cert.Init(cert_handle);
+  if (status != noErr)
+    return false;
+
+  x509_util::CSSMFieldValue subject;
+  status = cached_cert.GetField(&CSSMOID_X509V1SubjectNameStd, &subject);
+  if (status != CSSM_OK || !subject.field())
+    return false;
+
+  x509_util::CSSMFieldValue issuer;
+  status = cached_cert.GetField(&CSSMOID_X509V1IssuerNameStd, &issuer);
+  if (status != CSSM_OK || !issuer.field())
+    return false;
+
+  if (subject.field()->Length != issuer.field()->Length ||
+      memcmp(subject.field()->Data, issuer.field()->Data,
+             issuer.field()->Length) != 0) {
+    return false;
+  }
+
+  CSSM_CL_HANDLE cl_handle = CSSM_INVALID_HANDLE;
+  status = SecCertificateGetCLHandle(cert_handle, &cl_handle);
+  if (status)
+    return false;
+  CSSM_DATA cert_data;
+  status = SecCertificateGetData(cert_handle, &cert_data);
+  if (status)
+    return false;
+
+  if (CSSM_CL_CertVerify(cl_handle, 0, &cert_data, &cert_data, NULL, 0))
+    return false;
+  return true;
+}
+
 }  // namespace net