Reorganize net/disk_cache into backend specific directories.

net/disk_cache/v2/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__
+#ifndef NET_DISK_CACHE_V2_FILE_BLOCK_H__
+#define NET_DISK_CACHE_V2_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__
+#endif  // NET_DISK_CACHE_V2_FILE_BLOCK_H__