Get ClientCertStore through ResourceContext.

net/ssl/client_cert_store.h

 // 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.
 
 #ifndef NET_SSL_CLIENT_CERT_STORE_H_
 #define NET_SSL_CLIENT_CERT_STORE_H_
 
 #include "base/basictypes.h"
+#include "base/callback_forward.h"
 #include "net/base/net_export.h"
 #include "net/cert/x509_certificate.h"
 
 namespace net {
 
 class SSLCertRequestInfo;
 
+// The caller is expected to keep the ClientCertStore alive until the callback
+// supplied to GetClientCerts has been run.
 class NET_EXPORT ClientCertStore {
  public:
   virtual ~ClientCertStore() {}
 
-  virtual bool GetClientCerts(const SSLCertRequestInfo& cert_request_info,
-                              CertificateList* selected_certs) = 0;
+  // Get client certs matching the |cert_request_info|. On completion, the
+  // results will be stored in |selected_certs| and the |callback| will be run.
+  // The |callback| may be called sychronously.

[wtc, 2013/10/29 23:03:12]

This implies the memory that |selected_certs| points to must remain valid until
|callback| is called, right?

[mattm, 2013/10/29 23:59:01]

Yeah. I'll update comment to make that explicit too. 

+  virtual void GetClientCerts(const SSLCertRequestInfo& cert_request_info,
+                              CertificateList* selected_certs,
+                              const base::Closure& callback) = 0;
  protected:
   ClientCertStore() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ClientCertStore);
 };
 
 }  // namespace net
 
 #endif  // NET_SSL_CLIENT_CERT_STORE_H_