Remove the dependence on BrowserThread::FILE for

net/url_request/url_request_context_builder.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 "net/url_request/url_request_context_builder.h"
 
 #include <string>
 #include <utility>
 #include <vector>
 
@@ skipping 410 matching lines @@
     storage->set_throttler_manager(
         base::MakeUnique<URLRequestThrottlerManager>());
   }
 
   if (!proxy_service_) {
 #if !defined(OS_LINUX) && !defined(OS_ANDROID)
     // TODO(willchan): Switch to using this code when
     // ProxyService::CreateSystemProxyConfigService()'s signature doesn't suck.
     if (!proxy_config_service_) {
       proxy_config_service_ = ProxyService::CreateSystemProxyConfigService(
-          base::ThreadTaskRunnerHandle::Get().get(),
-          context->GetFileTaskRunner());
+          base::ThreadTaskRunnerHandle::Get().get());
     }
 #endif  // !defined(OS_LINUX) && !defined(OS_ANDROID)
     proxy_service_ =
         CreateProxyService(std::move(proxy_config_service_), context.get(),
                            context->host_resolver(),
                            context->network_delegate(), context->net_log());
     proxy_service_->set_quick_check_enabled(pac_quick_check_enabled_);
     proxy_service_->set_sanitize_url_policy(pac_sanitize_url_policy_);
   }
   storage->set_proxy_service(std::move(proxy_service_));
@@ skipping 86 matching lines @@
     std::unique_ptr<ProxyConfigService> proxy_config_service,
     URLRequestContext* url_request_context,
     HostResolver* host_resolver,
     NetworkDelegate* network_delegate,
     NetLog* net_log) {
   return ProxyService::CreateUsingSystemProxyResolver(
       std::move(proxy_config_service), net_log);
 }
 
 }  // namespace net