Fix NetLog thread safety issue

net/base/multi_threaded_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/multi_threaded_cert_verifier.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 134 matching lines @@
         flags_(flags),
         crl_set_(crl_set),
         origin_loop_(MessageLoop::current()),
         cert_verifier_(cert_verifier),
         canceled_(false),
         error_(ERR_FAILED) {
   }
 
   // Returns the certificate being verified. May only be called /before/
   // Start() is called.
-  X509Certificate* certificate() const { return cert_; }
+  scoped_refptr<const X509Certificate> certificate() const { return cert_; }
 
   bool Start() {
     DCHECK_EQ(MessageLoop::current(), origin_loop_);
 
     return base::WorkerPool::PostTask(
         FROM_HERE, base::Bind(&CertVerifierWorker::Run, base::Unretained(this)),
         true /* task is slow */);
   }
 
   // Cancel is called from the origin loop when the MultiThreadedCertVerifier is
@@ skipping 92 matching lines @@
 // lives only on the CertVerifier's origin message loop.
 class CertVerifierJob {
  public:
   CertVerifierJob(CertVerifierWorker* worker,
                   const BoundNetLog& net_log)
       : start_time_(base::TimeTicks::Now()),
         worker_(worker),
         net_log_(net_log) {
     net_log_.BeginEvent(
         NetLog::TYPE_CERT_VERIFIER_JOB,
-        base::Bind(&NetLogX509CertificateCallback,
-                   base::Unretained(worker_->certificate())));

[Ryan Sleevi, 2012/06/12 20:22:09]

This was safe as-is. Start() has not yet been called on |worker| (line 389), and
remains valid until HandleResult is called (line 201/205).

A temporary scoped_refptr<> would be created, since it's implicitly
constructable, so the change on 155 isn't necessary (and avoids one extra
AddRef/Release cycle)

+        CreateNetLogX509CertificateCallback(worker_->certificate()));
   }
 
   ~CertVerifierJob() {
     if (worker_) {
       net_log_.AddEvent(NetLog::TYPE_CANCELLED, NULL);
       net_log_.EndEvent(NetLog::TYPE_CERT_VERIFIER_JOB, NULL);
       worker_->Cancel();
       DeleteAllCanceled();
     }
   }
@@ skipping 168 matching lines @@
   DCHECK(CalledOnValidThread());
 
   ClearCache();
 }
 
 void MultiThreadedCertVerifier::SetCertVerifyProc(CertVerifyProc* verify_proc) {
   verify_proc_ = verify_proc;
 }
 
 }  // namespace net