Add HostCachePersistenceManager for Cronet

net/dns/host_cache.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_HOST_CACHE_H_
 #define NET_DNS_HOST_CACHE_H_
 
 #include <stddef.h>
 
 #include <functional>
@@ skipping 149 matching lines @@
            base::TimeTicks now,
            base::TimeDelta ttl);
 
   // Marks all entries as stale on account of a network change.
   void OnNetworkChange();
 
   void set_eviction_callback(const EvictionCallback& callback) {
     eviction_callback_ = callback;
   }
 
-  void set_persistence_delegate(PersistenceDelegate* delegate) {
-    delegate_ = delegate;
-  }
+  void set_persistence_delegate(PersistenceDelegate* delegate);
 
   // Empties the cache.
   void clear();
 
   // Clears hosts matching |host_filter| from the cache.
   void ClearForHosts(
       const base::Callback<bool(const std::string&)>& host_filter);
 
   // Returns the contents of the cache represented as a base::ListValue for
   // serialization.
@@ skipping 53 matching lines @@
   PersistenceDelegate* delegate_;
 
   THREAD_CHECKER(thread_checker_);
 
   DISALLOW_COPY_AND_ASSIGN(HostCache);
 };
 
 }  // namespace net
 
 #endif  // NET_DNS_HOST_CACHE_H_