Remove partial blockfile v3 disk_cache implementation.

net/disk_cache/blockfile/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_BLOCKFILE_BLOCK_FILES_H_
 #define NET_DISK_CACHE_BLOCKFILE_BLOCK_FILES_H_
 
 #include <stdint.h>
@@ skipping 63 matching lines @@
   bool ValidateCounters() const;
 
   // Returns the identifiers of this and the next file (0 if there is none).
   int FileId() const;
   int NextFileId() const;
 
   // Returns the size of the wrapped structure (BlockFileHeader).
   int Size() const;
 
   // Returns a pointer to the underlying BlockFileHeader.
-  // TODO(rvargas): This may be removed with the support for V2.
   BlockFileHeader* Header();
 
  private:
   BlockFileHeader* header_;
 };
 
 typedef std::vector<BlockHeader> BlockFilesBitmaps;
 
 // This class handles the set of block-files open by the disk cache.
 class NET_EXPORT_PRIVATE BlockFiles {
@@ skipping 68 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_BLOCKFILE_BLOCK_FILES_H_