Clean up dns prefetch code, and also port it.

chrome/browser/browser.scons

 # 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.
 
 Import('env')
 
 env = env.Clone()
 
 env.SConscript([
     '$CHROME_DIR/third_party/hunspell/using_hunspell.scons',
@@ skipping 401 matching lines @@
   ]),
   MSVSFilter('Net', [
     'net/chrome_url_request_context.cc',
     'net/chrome_url_request_context.h',
     'net/dns_global.cc',
     'net/dns_global.h',
     'net/dns_host_info.cc',
     'net/dns_host_info.h',
     'net/dns_master.cc',
     'net/dns_master.h',
-    'net/dns_slave.cc',
-    'net/dns_slave.h',
     'net/referrer.cc',
     'net/referrer.h',
     'net/resolve_proxy_msg_helper.cc',
     'net/resolve_proxy_msg_helper.h',
     'net/sdch_dictionary_fetcher.cc',
     'net/sdch_dictionary_fetcher.h',
     'net/url_fetcher.cc',
     'net/url_fetcher.h',
     'net/url_fetcher_protect.cc',
     'net/url_fetcher_protect.h',
@@ skipping 277 matching lines @@
       'importer/firefox2_importer.cc',
       'importer/firefox3_importer.cc',
       'importer/firefox_importer_utils.cc',
       'importer/ie_importer.cc',
       'importer/importer.cc',
       'importer/toolbar_importer.cc',
       'jankometer.cc',
       'login_prompt.cc',
       'memory_details.cc',
       'modal_html_dialog_delegate.cc',
-      'net/dns_global.cc',
-      'net/dns_master.cc',
-      'net/dns_slave.cc',
       'google_update.cc',
       'password_manager/encryptor.cc',
       'plugin_installer.cc',
       'plugin_process_host.cc',
       'plugin_service.cc',
       'printing/page_overlays.cc',
       'printing/print_job.cc',
       'printing/print_job_manager.cc',
       'printing/print_job_worker.cc',
       'printing/print_settings.cc',
@@ skipping 173 matching lines @@
 
 xmldoc_tool_list = [
     MSVSTool('VCCLCompilerTool',
              XMLDocumentationFileName=('$(IntDir)/$(InputName)1.xdc'),
              ObjectFile='$(IntDir)/$(InputName)1.obj'),
 ]
 
 for filename in xmldoc_files:
   p.AddFileConfig(filename, 'Debug|Win32', xmldoc_tool_list)
   p.AddFileConfig(filename, 'Release|Win32', xmldoc_tool_list)