Improve performance of proxy resolver by tracing DNS dependencies.

net/proxy/multi_threaded_proxy_resolver.h

 // 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.
 
 #ifndef NET_PROXY_MULTI_THREADED_PROXY_RESOLVER_H_
 #define NET_PROXY_MULTI_THREADED_PROXY_RESOLVER_H_
 
 #include <deque>
 #include <vector>
 
@@ skipping 80 matching lines @@
   virtual ~MultiThreadedProxyResolver();
 
   // ProxyResolver implementation:
   virtual int GetProxyForURL(const GURL& url,
                              ProxyInfo* results,
                              const CompletionCallback& callback,
                              RequestHandle* request,
                              const BoundNetLog& net_log) OVERRIDE;
   virtual void CancelRequest(RequestHandle request) OVERRIDE;
   virtual LoadState GetLoadState(RequestHandle request) const OVERRIDE;
-  virtual LoadState GetLoadStateThreadSafe(
-      RequestHandle request) const OVERRIDE;
   virtual void CancelSetPacScript() OVERRIDE;
   virtual void PurgeMemory() OVERRIDE;
   virtual int SetPacScript(
       const scoped_refptr<ProxyResolverScriptData>& script_data,
       const CompletionCallback& callback) OVERRIDE;
 
  private:
   class Executor;
   class Job;
   class SetPacScriptJob;
@@ skipping 23 matching lines @@
   const scoped_ptr<ProxyResolverFactory> resolver_factory_;
   const size_t max_num_threads_;
   PendingJobsQueue pending_jobs_;
   ExecutorList executors_;
   scoped_refptr<ProxyResolverScriptData> current_script_data_;
 };
 
 }  // namespace net
 
 #endif  // NET_PROXY_MULTI_THREADED_PROXY_RESOLVER_H_