chrome: Cleanup class/struct forward declarations

chrome/browser/media_galleries/chromeos/mtp_read_file_worker.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 CHROME_BROWSER_MEDIA_GALLERIES_CHROMEOS_MTP_READ_FILE_WORKER_H_
 #define CHROME_BROWSER_MEDIA_GALLERIES_CHROMEOS_MTP_READ_FILE_WORKER_H_
 
 #include <stdint.h>
 
 #include <memory>
 #include <string>
 
 #include "base/callback.h"
 #include "base/files/file.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 
-namespace base {
-class FilePath;
-}
-
 class SnapshotFileDetails;
 struct SnapshotRequestInfo;
 
 // Worker class to copy the contents of the media transfer protocol(MTP) device
 // file to the given snapshot file.
 class MTPReadFileWorker {
  public:
   explicit MTPReadFileWorker(const std::string& device_handle);
   ~MTPReadFileWorker();
 
@@ skipping 51 matching lines @@
   // The device unique identifier to query the device.
   const std::string device_handle_;
 
   // For callbacks that may run after destruction.
   base::WeakPtrFactory<MTPReadFileWorker> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MTPReadFileWorker);
 };
 
 #endif  // CHROME_BROWSER_MEDIA_GALLERIES_CHROMEOS_MTP_READ_FILE_WORKER_H_