DNS: Add stubs for persisting data across restarts

net/dns/dns_client.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_DNS_DNS_CLIENT_H_
 #define NET_DNS_DNS_CLIENT_H_
 
 #include <memory>
 
+#include "base/values.h"
 #include "net/base/net_export.h"
 #include "net/base/rand_callback.h"
 
 namespace net {
 
 class AddressSorter;
 class ClientSocketFactory;
 struct DnsConfig;
 class DnsTransactionFactory;
 class NetLog;
@@ skipping 11 matching lines @@
 
   // Returns NULL if the current config is not valid.
   virtual const DnsConfig* GetConfig() const = 0;
 
   // Returns NULL if the current config is not valid.
   virtual DnsTransactionFactory* GetTransactionFactory() = 0;
 
   // Returns NULL if the current config is not valid.
   virtual AddressSorter* GetAddressSorter() = 0;
 
+  // Does nothing if the current config is not valid.
+  virtual void ApplyPersistentData(const base::Value& data) = 0;
+
+  // Returns std::unique_ptr<const Value>(NULL) if the current config is not
+  // valid.
+  virtual std::unique_ptr<const base::Value> GetPersistentData() const = 0;
+
   // Creates default client.
   static std::unique_ptr<DnsClient> CreateClient(NetLog* net_log);
 
   // Creates a client for testing.  Allows using a mock ClientSocketFactory and
   // a deterministic random number generator. |socket_factory| must outlive
   // the returned DnsClient.
   static std::unique_ptr<DnsClient> CreateClientForTesting(
       NetLog* net_log,
       ClientSocketFactory* socket_factory,
       const RandIntCallback& rand_int_callback);
 };
 
 }  // namespace net
 
 #endif  // NET_DNS_DNS_CLIENT_H_