Clean up dns prefetch code, and also port it.

chrome/browser/net/dns_slave.h

-// Copyright (c) 2006-2008 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.
-
-// A DnsSlave object processes hostname lookups
-// via DNS on a single thread, waiting for that blocking
-// call to complete, and then getting its next hostname
-// from its associated DnsMaster object.
-// Since this class only is concerned with prefetching
-// to warm the underlying DNS cache, the actual IP
-// does not need to be recorded.  It is necessary to record
-// when the lookup finished, so that the associated DnsMaster
-// won't (wastefully) ask for the same name in "too short a
-// period of time."
-// This class does no "de-duping," and merely slavishly services
-// items supplied by its DnsMaster.
-
-#ifndef CHROME_BROWSER_NET_DNS_SLAVE_H_
-#define CHROME_BROWSER_NET_DNS_SLAVE_H_
-
-#include <windows.h>
-#include <string>
-
-#include "base/basictypes.h"
-
-namespace chrome_browser_net {
-
-class DnsMaster;
-class DnsSlave;
-
-// Support testing infrastructure, and allow off-line testing.
-typedef void (__stdcall *FreeAddrInfoFunction)(struct addrinfo* ai);
-typedef int (__stdcall *GetAddrInfoFunction)(const char* nodename,
-                                             const char* servname,
-                                             const struct addrinfo* hints,
-                                             struct addrinfo** result);
-void SetAddrinfoCallbacks(GetAddrInfoFunction getaddrinfo,
-                          FreeAddrInfoFunction freeaddrinfo);
-
-GetAddrInfoFunction get_getaddrinfo();
-FreeAddrInfoFunction get_freeaddrinfo();
-
-class DnsSlave {
- public:
-  DnsSlave(DnsMaster* master, size_t slave_index)
-      : master_(master),
-        slave_index_(slave_index) {
-  }
-
-  ~DnsSlave() {
-    master_ = NULL;
-  }
-
-  static DWORD WINAPI ThreadStart(void* pThis);
-
-  unsigned Run();
-
- private:
-  std::string hostname_;  // Name being looked up.
-
-  DnsMaster* master_;  // Master that started us.
-  size_t slave_index_;  // Our index into DnsMaster's array.
-
-  void BlockingDnsLookup();
-
-  DISALLOW_COPY_AND_ASSIGN(DnsSlave);
-};
-
-}  // namespace chrome_browser_net
-
-#endif  // CHROME_BROWSER_NET_DNS_SLAVE_H_
-