chrome: Cleanup class/struct forward declarations

chrome/browser/chromeos/file_system_provider/fileapi/file_stream_writer.h

 // Copyright 2014 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_CHROMEOS_FILE_SYSTEM_PROVIDER_FILEAPI_FILE_STREAM_WRITER_H_
 #define CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_FILEAPI_FILE_STREAM_WRITER_H_
 
 #include <stdint.h>
 
 #include "base/files/file.h"
 #include "base/files/file_path.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "storage/browser/fileapi/file_stream_writer.h"
 #include "storage/browser/fileapi/file_system_url.h"
 
 namespace chromeos {
 namespace file_system_provider {
 
-class ProvidedFileSystemInterface;
-
 // Implements a streamed file writer. It is lazily initialized by the first call
 // to Write().
 class FileStreamWriter : public storage::FileStreamWriter {
  public:
   FileStreamWriter(const storage::FileSystemURL& url, int64_t initial_offset);
 
   ~FileStreamWriter() override;
 
   // storage::FileStreamWriter overrides.
   int Write(net::IOBuffer* buf,
@@ skipping 49 matching lines @@
   State state_;
 
   base::WeakPtrFactory<FileStreamWriter> weak_ptr_factory_;
   DISALLOW_COPY_AND_ASSIGN(FileStreamWriter);
 };
 
 }  // namespace file_system_provider
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_FILEAPI_FILE_STREAM_WRITER_H_