No work needs to be done in Metal for cross-context textures. Metal
automatically places a barrier between different command buffer
encoders, and Skia and the external client will implicitly be using
different encoders.
Bug: skia:8243
Change-Id: I0c855e2d78aa8973f389108483184947f019342c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/256699
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
55276e3e01