tree fef91115fa9f94954e17f3075d96ebd8a2100c0b
parent 8c566be72fd4d2cf7aab9accaa5b869e5bcc73f0
author Shawn Pearce <spearce@spearce.org> 1499129314 -0700
committer Shawn Pearce <spearce@spearce.org> 1500304537 -0700

Extract BlockBasedFile base class for DfsPackFile

This new base class has the minimum set of properties and methods
necessary for DfsBlockCache to manage blocks of a file in the cache.
Subclasses can use DfsBlockCache for any content.

This refactoring opens the door for additional PackExt types other
than PACK to be stored on a block-by-block basis by the DfsBlockCache.

Change-Id: I307228fc805c3ff0c596783beb24fd52bec35ba8