Fix NetLog thread safety issue

net/base/x509_certificate_net_log_param.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_net_log_param.h"
 
 #include <string>
 #include <vector>
 
+#include "base/bind.h"
 #include "base/values.h"
 #include "net/base/x509_certificate.h"
 
 namespace net {
 
-base::Value* NetLogX509CertificateCallback(const X509Certificate* certificate,
-                                           NetLog::LogLevel log_level) {
+namespace {
+
+Value* NetLogX509CertificateCallback(
+    scoped_refptr<const X509Certificate> certificate,
+    NetLog::LogLevel log_level) {
   DictionaryValue* dict = new DictionaryValue();
   ListValue* certs = new ListValue();
   std::vector<std::string> encoded_chain;
   certificate->GetPEMEncodedChain(&encoded_chain);
   for (size_t i = 0; i < encoded_chain.size(); ++i)
     certs->Append(base::Value::CreateStringValue(encoded_chain[i]));
   dict->Set("certificates", certs);
   return dict;
 }
 
+}  // namespace
+
+NetLog::ParametersCallback CreateNetLogX509CertificateCallback(
+    scoped_refptr<const X509Certificate> certificate) {
+  return base::Bind(&NetLogX509CertificateCallback, certificate);
+}
+
 }  // namespace net