GrContext::copyTexture->GrContext::copySurface.

Add a flush writes pixel ops flag.

Add an explicit flush writes for GrSurface.

BUG=skia:2977

Committed: https://skia.googlesource.com/skia/+/cf99b00980b6c9c557e71abf1a7c9f9b21217262

Review URL: https://codereview.chromium.org/622663002
7 files changed