chrome: Cleanup class/struct forward declarations

chrome/browser/media_galleries/win/mtp_device_delegate_impl_win.h

 // Copyright (c) 2013 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_WIN_MTP_DEVICE_DELEGATE_IMPL_WIN_H_
 #define CHROME_BROWSER_MEDIA_GALLERIES_WIN_MTP_DEVICE_DELEGATE_IMPL_WIN_H_
 
 #include <stdint.h>
 
 #include <memory>
 #include <queue>
 
 #include "base/callback.h"
 #include "base/files/file.h"
 #include "base/location.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/strings/string16.h"
 #include "base/win/scoped_comptr.h"
 #include "chrome/browser/media_galleries/fileapi/mtp_device_async_delegate.h"
 #include "storage/browser/fileapi/async_file_util.h"
 
 namespace base {
 class FilePath;
 class SequencedTaskRunner;
 }
 
 class SnapshotFileDetails;
-struct SnapshotRequestInfo;
 
 // MTPDeviceDelegateImplWin is used to communicate with the media transfer
 // protocol (MTP) device to complete file system operations. These operations
 // are performed asynchronously on a blocking pool thread since the device
 // access may be slow and may take a long time to complete. MTP
 // device can have multiple data storage partitions. MTPDeviceDelegateImplWin
 // is instantiated per MTP device storage partition using
 // CreateMTPDeviceAsyncDelegate(). MTPDeviceDelegateImplWin lives on the IO
 // thread.
 class MTPDeviceDelegateImplWin : public MTPDeviceAsyncDelegate {
@@ skipping 220 matching lines @@
   // Used to make sure only one task is in progress at any time.
   bool task_in_progress_;
 
   // For callbacks that may run after destruction.
   base::WeakPtrFactory<MTPDeviceDelegateImplWin> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MTPDeviceDelegateImplWin);
 };
 
 #endif  // CHROME_BROWSER_MEDIA_GALLERIES_WIN_MTP_DEVICE_DELEGATE_IMPL_WIN_H_