Retract GrContext from src/gpu/effects

Change-Id: Iceb7263098286bafb2605ef17d1fe6bb25d71e97
Reviewed-on: https://skia-review.googlesource.com/9693
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
70 files changed