SK_ONCE for SkData and SkPathRef

Adds SK_ONCE_FRIEND, to allow SK_DEF_ONCE code to be friends with a class.  This had to go in include/core to be visible to headers there.

BUG=
R=reed@google.com, bungeman@google.com

Author: mtklein@google.com

Review URL: https://codereview.chromium.org/26491003

git-svn-id: http://skia.googlecode.com/svn/trunk/include@11914 2bbb7eff-a529-9590-31e7-b0007b416f81
2 files changed