Parse an application/x-x509-user-cert response with

net/base/x509_certificate_nss.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/base/x509_certificate.h"
 
 #include <cert.h>
 #include <cryptohi.h>
 #include <keyhi.h>
 #include <nss.h>
@@ skipping 173 matching lines @@
       // TODO(gspencer): internationalize this: it's wrong to
       // hard code English.
 
       std::string username, ca_name;
       char* temp_username = CERT_GetCommonName(
           &cert_handle_->subject);
       char* temp_ca_name = CERT_GetCommonName(&cert_handle_->issuer);
       if (temp_username) {
         username = temp_username;
         PORT_Free(temp_username);
+      } else {
+        username = CERT_GetFirstEmailAddress(cert_handle_);
       }
       if (temp_ca_name) {
         ca_name = temp_ca_name;
         PORT_Free(temp_ca_name);
       }
       result = username + "'s " + ca_name + " ID";
       break;
     }
     case SERVER_CERT:
       result = subject_.GetDisplayName();
@@ skipping 263 matching lines @@
       *type = kPublicKeyTypeECDSA;
       break;
     default:
       *type = kPublicKeyTypeUnknown;
       *size_bits = 0;
       break;
   }
 }
 
 }  // namespace net