Clean up coding style

net/url_request/url_fetcher_impl.h

 // Copyright (c) 2012 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.
 
 // This file contains URLFetcher, a wrapper around URLRequest that handles
 // low-level details like thread safety, ref counting, and incremental buffer
 // reading.  This is useful for callers who simply want to get the data from a
 // URL and don't care about all the nitty-gritty details.
 //
 // NOTE(willchan): Only one "IO" thread is supported for URLFetcher.  This is a
 // temporary situation.  We will work on allowing support for multiple "io"
 // threads per process.
 
 #ifndef NET_URL_REQUEST_URL_FETCHER_IMPL_H_
 #define NET_URL_REQUEST_URL_FETCHER_IMPL_H_
 
+#include <string>
+
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "net/base/net_export.h"
 #include "net/url_request/url_fetcher.h"
 
 namespace net {
 class URLFetcherCore;
 class URLFetcherDelegate;
 class URLFetcherFactory;
 
@@ skipping 93 matching lines @@
   static int GetNumFetcherCores();
 
   const scoped_refptr<URLFetcherCore> core_;
 
   DISALLOW_COPY_AND_ASSIGN(URLFetcherImpl);
 };
 
 }  // namespace net
 
 #endif  // NET_URL_REQUEST_URL_FETCHER_IMPL_H_