Remove some unnecessary uses of SkOnce.

  - gm/imagefiltersgraph.cpp can just use a global registrar
  - SkScaledImageCache always accesses its global under a lock

BUG=skia:
R=bungeman@google.com, mtklein@google.com

Author: mtklein@chromium.org

Review URL: https://codereview.chromium.org/297273006

git-svn-id: http://skia.googlecode.com/svn/trunk@14897 2bbb7eff-a529-9590-31e7-b0007b416f81
2 files changed