Disk cache: Introduce BlockBitmaps for V3.

net/disk_cache/disk_format_base.h

 // Copyright (c) 2011 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.
 
 // For a general description of the files used by the cache see file_format.h.
 //
 // A block file is a file designed to store blocks of data of a given size. It
 // is able to store data that spans from one to four consecutive "blocks", and
 // it grows as needed to store up to approximately 65000 blocks. It has a fixed
 // size header used for book keeping such as tracking free of blocks on the
@@ skipping 10 matching lines @@
 #define NET_DISK_CACHE_DISK_FORMAT_BASE_H_
 
 #include "base/basictypes.h"
 #include "net/base/net_export.h"
 
 namespace disk_cache {
 
 typedef uint32 CacheAddr;
 
 const uint32 kBlockVersion2 = 0x20000;  // Version 2.0.
+const uint32 kBlockCurrentVersion = 0x30000;  // Version 3.0.
 
 const uint32 kBlockMagic = 0xC104CAC3;
 const int kBlockHeaderSize = 8192;  // Two pages: almost 64k entries
 const int kMaxBlocks = (kBlockHeaderSize - 80) * 8;
 
 // Bitmap to track used blocks on a block-file.
 typedef uint32 AllocBitmap[kMaxBlocks / 32];
 
 // A block-file is the file used to store information in blocks (could be
 // EntryStore blocks, RankingsNode blocks or user-data blocks).
@@ skipping 80 matching lines @@
 };
 
 // The number of blocks stored by a child entry.
 const int kNumSparseBits = 1024;
 COMPILE_ASSERT(sizeof(SparseData) == sizeof(SparseHeader) + kNumSparseBits / 8,
                Invalid_SparseData_bitmap);
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_DISK_FORMAT_BASE_H_