Implement TLS client auth in the OS X OpenSSL port.

net/ssl/openssl_client_key_store.h

 // Copyright (c) 2013 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.
 
 #ifndef NET_SSL_OPENSSL_CLIENT_KEY_STORE_H_
 #define NET_SSL_OPENSSL_CLIENT_KEY_STORE_H_
 
 #include <openssl/evp.h>
 
 #include <vector>
@@ skipping 31 matching lines @@
   // certificate's private key.
   // Returns false if an error occured.
   // This function does not take ownership of the private_key, but may
   // increment its internal reference count.
   NET_EXPORT bool RecordClientCertPrivateKey(const X509Certificate* cert,
                                              EVP_PKEY* private_key);
 
   // Given a certificate's |public_key|, return the corresponding private
   // key that has been recorded previously by RecordClientCertPrivateKey().
   // |cert| is a client certificate.
-  // |*private_key| will be reset to its matching private key on success.
-  // Returns true on success, false otherwise. This increments the reference
-  // count of the private key on success.
-  bool FetchClientCertPrivateKey(const X509Certificate* cert,
-                                 crypto::ScopedEVP_PKEY* private_key);
+  // Returns its matching private key on success, NULL otherwise.
+  crypto::ScopedEVP_PKEY FetchClientCertPrivateKey(const X509Certificate* cert);
 
   // Flush all recorded keys.
   void Flush();
 
  protected:
   OpenSSLClientKeyStore();
 
   ~OpenSSLClientKeyStore();
 
   // Adds a given public/private key pair.
@@ skipping 25 matching lines @@
   std::vector<KeyPair> pairs_;
 
   friend struct DefaultSingletonTraits<OpenSSLClientKeyStore>;
 
   DISALLOW_COPY_AND_ASSIGN(OpenSSLClientKeyStore);
 };
 
 }  // namespace net
 
 #endif  // NET_SSL_OPENSSL_CLIENT_KEY_STORE_H_