chrome: Cleanup class/struct forward declarations

chrome/browser/net/spdyproxy/data_reduction_proxy_chrome_io_data.h

 // Copyright 2015 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 CHROME_BROWSER_NET_SPDYPROXY_DATA_REDUCTION_PROXY_CHROME_IO_DATA_H_
 #define CHROME_BROWSER_NET_SPDYPROXY_DATA_REDUCTION_PROXY_CHROME_IO_DATA_H_
 
 #include <memory>
 
 #include "base/memory/ref_counted.h"
 
-class DataReductionProxyChromeConfigurator;
 class PrefService;
 
 namespace base {
 class SingleThreadTaskRunner;
 }
 
 namespace data_reduction_proxy {
 class DataReductionProxyIOData;
 }
 
 namespace net {
 class NetLog;
 }
 
 // Constructs DataReductionProxyIOData suitable for use by ProfileImpl and
 // ProfileImplIOData.
 std::unique_ptr<data_reduction_proxy::DataReductionProxyIOData>
 CreateDataReductionProxyChromeIOData(
     net::NetLog* net_log,
     PrefService* prefs,
     const scoped_refptr<base::SingleThreadTaskRunner>& io_thread_runner,
     const scoped_refptr<base::SingleThreadTaskRunner>& ui_thread_runner);
 
 #endif  // CHROME_BROWSER_NET_SPDYPROXY_DATA_REDUCTION_PROXY_CHROME_IO_DATA_H_