content: Cleanup class/struct forward declarations

content/browser/download/download_file_factory.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.
 //
 #ifndef CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_FILE_FACTORY_H_
 #define CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_FILE_FACTORY_H_
 
 #include <memory>
 
 #include "base/files/file.h"
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "content/common/content_export.h"
 #include "url/gurl.h"
 
-namespace crypto {
-class SecureHash;
-}
-
 namespace net {
 class NetLogWithSource;
 }
 
 namespace content {
 
 class ByteStreamReader;
 class DownloadDestinationObserver;
 class DownloadFile;
-class DownloadManager;
 struct DownloadSaveInfo;
 
 class CONTENT_EXPORT DownloadFileFactory {
  public:
   virtual ~DownloadFileFactory();
 
   virtual DownloadFile* CreateFile(
       std::unique_ptr<DownloadSaveInfo> save_info,
       const base::FilePath& default_downloads_directory,
       std::unique_ptr<ByteStreamReader> byte_stream,
       const net::NetLogWithSource& net_log,
       base::WeakPtr<DownloadDestinationObserver> observer);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_FILE_FACTORY_H_