Reorganize net/disk_cache into backend specific directories.

net/disk_cache/file_block.h

-// Copyright (c) 2006-2008 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.
-
-// See net/disk_cache/disk_cache.h for the public interface of the cache.
-
-#ifndef NET_DISK_CACHE_FILE_BLOCK_H__
-#define NET_DISK_CACHE_FILE_BLOCK_H__
-
-namespace disk_cache {
-
-// This interface exposes common functionality for a single block of data
-// stored on a file-block, regardless of the real type or size of the block.
-// Used to simplify loading / storing the block from disk.
-class FileBlock {
- public:
-  virtual ~FileBlock() {}
-
-  // Returns a pointer to the actual data.
-  virtual void* buffer() const = 0;
-
-  // Returns the size of the block;
-  virtual size_t size() const = 0;
-
-  // Returns the file offset of this block.
-  virtual int offset() const = 0;
-};
-
-}  // namespace disk_cache
-
-#endif  // NET_DISK_CACHE_FILE_BLOCK_H__