Improve performance of proxy resolver by tracing DNS dependencies.

net/proxy/proxy_resolver_winhttp.cc

 // Copyright (c) 2011 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/proxy/proxy_resolver_winhttp.h"
 
 #include <windows.h>
 #include <winhttp.h>
 
 #include "base/metrics/histogram.h"
@@ skipping 110 matching lines @@
 void ProxyResolverWinHttp::CancelRequest(RequestHandle request) {
   // This is a synchronous ProxyResolver; no possibility for async requests.
   NOTREACHED();
 }
 
 LoadState ProxyResolverWinHttp::GetLoadState(RequestHandle request) const {
   NOTREACHED();
   return LOAD_STATE_IDLE;
 }
 
-LoadState ProxyResolverWinHttp::GetLoadStateThreadSafe(
-    RequestHandle request) const {
-  return LOAD_STATE_IDLE;
-}
-
 void ProxyResolverWinHttp::CancelSetPacScript() {
   NOTREACHED();
 }
 
 int ProxyResolverWinHttp::SetPacScript(
     const scoped_refptr<ProxyResolverScriptData>& script_data,
     const CompletionCallback& /*callback*/) {
   if (script_data->type() == ProxyResolverScriptData::TYPE_AUTO_DETECT) {
     pac_url_ = GURL("http://wpad/wpad.dat");
   } else {
@@ skipping 23 matching lines @@
 }
 
 void ProxyResolverWinHttp::CloseWinHttpSession() {
   if (session_handle_) {
     WinHttpCloseHandle(session_handle_);
     session_handle_ = NULL;
   }
 }
 
 }  // namespace net