Add CertIssuerSourceAia: authorityInfoAccess fetching for CertPathBuilder.

net/cert/internal/cert_issuer_source_aia.h

Index: net/cert/internal/cert_issuer_source_aia.h
diff --git a/net/cert/internal/cert_issuer_source_aia.h b/net/cert/internal/cert_issuer_source_aia.h
new file mode 100644
index 0000000000000000000000000000000000000000..e0c7fe77676f536a8f4c78cd9af33c45321f8df5
--- /dev/null
+++ b/net/cert/internal/cert_issuer_source_aia.h
@@ -0,0 +1,40 @@
+// 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/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);
+  ~CertIssuerSourceAia() override;
+
+  // CertIssuerSource implementation:
+  void SyncGetIssuersOf(
+      const ParsedCertificate* cert,
+      std::vector<scoped_refptr<ParsedCertificate>>* issuers) override;
+  void AsyncGetIssuersOf(const ParsedCertificate* cert,
+                         const IssuerCallback& issuers_callback,
+                         std::unique_ptr<Request>* out_req) override;
+
+ private:
+  CertNetFetcher* cert_fetcher_;
+
+  DISALLOW_COPY_AND_ASSIGN(CertIssuerSourceAia);
+};
+
+}  // namespace net
+
+#endif  // NET_CERT_INTERNAL_CERT_ISSUER_SOURCE_AIA_H_