Remove unused SkBitmapCacheDesc factory

Bug: skia:
Change-Id: I1b04e533f23bd07333feee5a14986bffd7f43934
Reviewed-on: https://skia-review.googlesource.com/c/163788
Auto-Submit: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
2 files changed