Add Cronet experimental option for host cache persistence

components/cronet/url_request_context_config.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 COMPONENTS_CRONET_URL_REQUEST_CONTEXT_CONFIG_H_
 #define COMPONENTS_CRONET_URL_REQUEST_CONTEXT_CONFIG_H_
 
 #include <memory>
 #include <string>
 #include <vector>
@@ skipping 149 matching lines @@
 
   // Data to populte CertVerifierCache.
   const std::string cert_verifier_data;
 
   // App-provided list of servers that support QUIC.
   std::vector<std::unique_ptr<QuicHint>> quic_hints;
 
   // The list of public key pins.
   std::vector<std::unique_ptr<Pkp>> pkp_list;
 
+  // Enable DNS cache persistence.
+  bool enable_host_cache_persistence = false;
+
+  // Minimum time in milliseconds between writing the HostCache contents to
+  // prefs. Only relevant when |enable_host_cache_persistence| is true.
+  int host_cache_persistence_delay_ms = 60000;
+
   // Experimental options that are recognized by the config parser.
   std::unique_ptr<base::DictionaryValue> effective_experimental_options =
       nullptr;
 
  private:
   // Parses experimental options and makes appropriate changes to settings in
   // the URLRequestContextConfig and URLRequestContextBuilder.
   void ParseAndSetExperimentalOptions(
       net::URLRequestContextBuilder* context_builder,
       net::NetLog* net_log,
@@ skipping 56 matching lines @@
   // Data to populate CertVerifierCache.
   std::string cert_verifier_data = "";
 
  private:
   DISALLOW_COPY_AND_ASSIGN(URLRequestContextConfigBuilder);
 };
 
 }  // namespace cronet
 
 #endif  // COMPONENTS_CRONET_URL_REQUEST_CONTEXT_CONFIG_H_