content: Cleanup class/struct forward declarations

content/browser/download/download_file.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_H_
 #define CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_FILE_H_
 
 #include <stdint.h>
 
 #include <string>
 
 #include "base/callback_forward.h"
 #include "base/files/file_path.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/download_interrupt_reasons.h"
 
 class GURL;
 
 namespace content {
 
-class DownloadManager;
-
 // These objects live exclusively on the file thread and handle the writing
 // operations for one download. These objects live only for the duration that
 // the download is 'in progress': once the download has been completed or
 // cancelled, the DownloadFile is destroyed.
 class CONTENT_EXPORT DownloadFile {
  public:
   // Callback used with Initialize.  On a successful initialize, |reason| will
   // be DOWNLOAD_INTERRUPT_REASON_NONE; on a failed initialize, it will be
   // set to the reason for the failure.
   typedef base::Callback<void(DownloadInterruptReason reason)>
@@ skipping 35 matching lines @@
   // Abort the download and automatically close the file.
   virtual void Cancel() = 0;
 
   virtual const base::FilePath& FullPath() const = 0;
   virtual bool InProgress() const = 0;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_FILE_H_