Implement SkImageFilter::Cache with SkResourceCache.

The single global cache now uses the global SkResourceCache,
and any Create()ed cache uses a local SkResourceCache.

No real public API changes (and only deletes).

I don't see any pixel diffs on .skps or GMs.
Don't see any significant perf difference on 8888 or gpu configs.
DM peak memory usage did drop by about 113M, close to the 128M cache size.

BUG=skia:3662

Landing PS8 temporarily to trigger the perf bots.
TBR=reed@google.com

Review URL: https://codereview.chromium.org/1370323002
3 files changed