Move ASCIIToWide and ASCIIToUTF16 to utf_string_conversions.h. I've found it...

chrome/browser/net/preconnect.cc

 // Copyright (c) 2010 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/preconnect.h"
 
 #include "base/histogram.h"
 #include "base/logging.h"
+#include "base/string_util.h"
 #include "chrome/browser/profile.h"
 #include "chrome/browser/chrome_thread.h"
 #include "chrome/common/net/url_request_context_getter.h"
 #include "net/base/host_port_pair.h"
 #include "net/http/http_network_session.h"
 #include "net/http/http_transaction_factory.h"
 #include "net/proxy/proxy_service.h"
 #include "net/url_request/url_request_context.h"
 
 namespace chrome_browser_net {
@@ skipping 107 matching lines @@
   handle.Init(group_name, tcp_params, net::LOWEST, callback_instance_, pool,
               net::BoundNetLog());
   handle.Reset();
 }
 
 void Preconnect::RunWithParams(const Tuple1<int>& params) {
   // This will rarely be called, as we reset the connection just after creating.
   NOTREACHED();
 }
 }  // chrome_browser_net