Create stubs for system certificate validation.

net/base/single_request_cert_verifier.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/single_request_cert_verifier.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "net/base/net_errors.h"
 #include "net/base/x509_certificate.h"
@@ skipping 17 matching lines @@
 int SingleRequestCertVerifier::Verify(X509Certificate* cert,
                                       const std::string& hostname,
                                       int flags,
                                       CRLSet* crl_set,
                                       CertVerifyResult* verify_result,
                                       const CompletionCallback& callback,
                                       const BoundNetLog& net_log) {
   // Should not be already in use.
   DCHECK(!cur_request_ && cur_request_callback_.is_null());
 
-  // Do a synchronous verification.

[Ryan Sleevi, 2012/03/03 05:01:50]

I checked every user of SingleRequestCertVerifier, and they all provide
callbacks. Plus, I believe SingleRequestCertVerifier should be ignorant about
sync vs async here.

[wtc, 2012/03/06 23:10:14]

I guess we can replace this with a DCHECK?  The code below
won't work if cert_verifier_->Verify() returns ERR_IO_PENDING
but callback is null.

-  if (callback.is_null())
-    return cert->Verify(hostname, flags, crl_set, verify_result);
-
   CertVerifier::RequestHandle request = NULL;
 
   // We need to be notified of completion before |callback| is called, so that
   // we can clear out |cur_request_*|.
   int rv = cert_verifier_->Verify(
       cert, hostname, flags, crl_set, verify_result,
       base::Bind(&SingleRequestCertVerifier::OnVerifyCompletion,
                  base::Unretained(this)),
       &request, net_log);
 
@@ skipping 13 matching lines @@
 
   // Clear the outstanding request information.
   cur_request_ = NULL;
   cur_request_callback_.Reset();
 
   // Call the user's original callback.
   callback.Run(result);
 }
 
 }  // namespace net