Check effective proxy config before adding data reduction proxies

net/proxy/proxy_service.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_PROXY_PROXY_SERVICE_H_
 #define NET_PROXY_PROXY_SERVICE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 192 matching lines @@
   // ResolveProxy calls. ProxyService takes ownership of
   // |new_proxy_config_service|.
   void ResetConfigService(ProxyConfigService* new_proxy_config_service);
 
   // Returns the last configuration fetched from ProxyConfigService.
   const ProxyConfig& fetched_config() {
     return fetched_config_;
   }
 
   // Returns the current configuration being used by ProxyConfigService.
-  const ProxyConfig& config() {
+  const ProxyConfig& config() const {
     return config_;
   }
 
   // Returns the map of proxies which have been marked as "bad".
   const ProxyRetryInfoMap& proxy_retry_info() const {
     return proxy_retry_info_;
   }
 
   // Clears the list of bad proxy servers that has been cached.
   void ClearBadProxiesCache() {
@@ skipping 223 matching lines @@
 
   // Whether child ProxyScriptDeciders should use QuickCheck
   bool quick_check_enabled_;
 
   DISALLOW_COPY_AND_ASSIGN(ProxyService);
 };
 
 }  // namespace net
 
 #endif  // NET_PROXY_PROXY_SERVICE_H_