Do not persist HttpServerProperties to disk that often.

net/http/http_server_properties_manager.h

 // Copyright 2014 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_HTTP_HTTP_SERVER_PROPERTIES_MANAGER_H_
 #define NET_HTTP_HTTP_SERVER_PROPERTIES_MANAGER_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 296 matching lines @@
 
   // --------------
   // Network thread
   // --------------
 
   const scoped_refptr<base::SequencedTaskRunner> network_task_runner_;
 
   // Used to post |prefs::kHttpServerProperties| pref update tasks.
   std::unique_ptr<base::OneShotTimer> network_prefs_update_timer_;
 
+  // Time of last UpdatePrefsFromCacheOnNetworkThread() execution.
+  base::Time last_update_prefs_from_cache_;
+
   std::unique_ptr<HttpServerPropertiesImpl> http_server_properties_impl_;
 
   // Used to get |weak_ptr_| to self on the pref thread.
   std::unique_ptr<base::WeakPtrFactory<HttpServerPropertiesManager>>
       pref_weak_ptr_factory_;
 
   // Used to get |weak_ptr_| to self on the network thread.
   std::unique_ptr<base::WeakPtrFactory<HttpServerPropertiesManager>>
       network_weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(HttpServerPropertiesManager);
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP_HTTP_SERVER_PROPERTIES_MANAGER_H_