Improve performance of proxy resolver by tracing DNS dependencies.

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 "base/command_line.h"
 #include "base/string_number_conversions.h"
 #include "base/threading/thread.h"
 #include "chrome/browser/browser_process.h"
@@ skipping 99 matching lines @@
 #if defined(OS_IOS)
     NOTREACHED();
 #else
     net::DhcpProxyScriptFetcherFactory dhcp_factory;
     if (command_line.HasSwitch(switches::kDisableDhcpWpad)) {
       dhcp_factory.set_enabled(false);
     }
 
     proxy_service = net::CreateProxyServiceUsingV8ProxyResolver(
         proxy_config_service,
-        num_pac_threads,
         new net::ProxyScriptFetcherImpl(context),
         dhcp_factory.Create(context),
         context->host_resolver(),
         net_log,
         context->network_delegate());
 #endif  // defined(OS_IOS)
   } else {
     proxy_service = net::ProxyService::CreateUsingSystemProxyResolver(
         proxy_config_service,
         num_pac_threads,
         net_log);
   }
 
   return proxy_service;
 }