Remove the dependence on BrowserThread::FILE for

chrome/browser/net/proxy_service_factory.cc

 // 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.
 
 #include "chrome/browser/net/proxy_service_factory.h"
 
 #include <stddef.h>
 #include <string>
 #include <utility>
 
@@ skipping 34 matching lines @@
 
 #if !defined(OS_CHROMEOS)
   // On ChromeOS, base service is NULL; chromeos::ProxyConfigServiceImpl
   // determines the effective proxy config to take effect in the network layer,
   // be it from prefs or system (which is network shill on chromeos).
 
   // For other platforms, create a baseline service that provides proxy
   // configuration in case nothing is configured through prefs (Note: prefs
   // include command line and configuration policy).
 
-  // TODO(port): the IO and FILE message loops are only used by Linux.  Can
-  // that code be moved to chrome/browser instead of being in net, so that it
-  // can use BrowserThread instead of raw MessageLoop pointers? See bug 25354.
   base_service = net::ProxyService::CreateSystemProxyConfigService(
-      BrowserThread::GetTaskRunnerForThread(BrowserThread::IO),
-      BrowserThread::GetTaskRunnerForThread(BrowserThread::FILE));
+      BrowserThread::GetTaskRunnerForThread(BrowserThread::IO));
 #endif  // !defined(OS_CHROMEOS)
 
   return tracker->CreateTrackingProxyConfigService(std::move(base_service));
 }
 
 // static
 PrefProxyConfigTracker*
 ProxyServiceFactory::CreatePrefProxyConfigTrackerOfProfile(
     PrefService* profile_prefs,
     PrefService* local_state_prefs) {
@@ skipping 64 matching lines @@
   }
 
   proxy_service->set_quick_check_enabled(quick_check_enabled);
   proxy_service->set_sanitize_url_policy(
       pac_https_url_stripping_enabled
           ? net::ProxyService::SanitizeUrlPolicy::SAFE
           : net::ProxyService::SanitizeUrlPolicy::UNSAFE);
 
   return proxy_service;
 }