Allow CertNetFetcher to be shutdown from the network thread

net/cert/internal/cert_issuer_source_aia.h

 // Copyright 2016 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_CERT_INTERNAL_CERT_ISSUER_SOURCE_AIA_H_
 #define NET_CERT_INTERNAL_CERT_ISSUER_SOURCE_AIA_H_
 
 #include "base/strings/string_piece.h"
 #include "net/base/net_export.h"
 #include "net/cert/internal/cert_issuer_source.h"
 
 namespace net {
 
 class CertNetFetcher;
 
 class NET_EXPORT CertIssuerSourceAia : public CertIssuerSource {
  public:
   // Creates CertIssuerSource that will use |cert_fetcher| to retrieve issuers
-  // using AuthorityInfoAccess URIs. |cert_fetcher| must outlive the
-  // CertIssuerSourceAia.  CertIssuerSourceAia must be created and used only on
-  // a single thread, which is the thread |cert_fetcher| will be operated from.
-  explicit CertIssuerSourceAia(CertNetFetcher* cert_fetcher);
+  // using AuthorityInfoAccess URIs. CertIssuerSourceAia must be created and
+  // used only on a single thread, which is the thread |cert_fetcher| will be
+  // operated from.
+  explicit CertIssuerSourceAia(scoped_refptr<CertNetFetcher> cert_fetcher);
   ~CertIssuerSourceAia() override;
 
   // CertIssuerSource implementation:
   void SyncGetIssuersOf(const ParsedCertificate* cert,
                         ParsedCertificateList* issuers) override;
   void AsyncGetIssuersOf(const ParsedCertificate* cert,
                          std::unique_ptr<Request>* out_req) override;
 
  private:
-  CertNetFetcher* cert_fetcher_;
+  scoped_refptr<CertNetFetcher> cert_fetcher_;
 
   DISALLOW_COPY_AND_ASSIGN(CertIssuerSourceAia);
 };
 
 }  // namespace net
 
 #endif  // NET_CERT_INTERNAL_CERT_ISSUER_SOURCE_AIA_H_