Disk cache: Introduce BlockBitmaps for V3.

net/disk_cache/block_files.h

 // Copyright (c) 2012 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.
 
 #ifndef NET_DISK_CACHE_BLOCK_FILES_H_
 #define NET_DISK_CACHE_BLOCK_FILES_H_
 
 #include <vector>
@@ skipping 31 matching lines @@
   void DeleteMapBlock(int index, int block_size);
 
   // Returns true if the specified block is used.
   bool UsedMapBlock(int index, int size);
 
   // Restores the "empty counters" and allocation hints.
   void FixAllocationCounters();
 
   // Returns true if the current block file should not be used as-is to store
   // more records. |block_count| is the number of blocks to allocate.
-  bool NeedToGrowBlockFile(int block_count);
+  bool NeedToGrowBlockFile(int block_count) const;
+
+  // Returns true if this block file can be used to store an extra record of
+  // size |block_count|.
+  bool CanAllocate(int block_count) const;
 
   // Returns the number of empty blocks for this file.
   int EmptyBlocks() const;
 
   // Returns true if the counters look OK.
   bool ValidateCounters() const;
 
   // Returns the size of the wrapped structure (BlockFileHeader).
   int Size() const;
 
@@ skipping 80 matching lines @@
   FRIEND_TEST_ALL_PREFIXES(DiskCacheTest, BlockFiles_TruncatedFile);
   FRIEND_TEST_ALL_PREFIXES(DiskCacheTest, BlockFiles_InvalidFile);
   FRIEND_TEST_ALL_PREFIXES(DiskCacheTest, BlockFiles_Stats);
 
   DISALLOW_COPY_AND_ASSIGN(BlockFiles);
 };
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_BLOCK_FILES_H_