Update command buffer and finishProc processing in Metal
* Restructure GrMtlGpu::submitCommandBuffer() to handle empty
command buffers better and ensure that finishedCallbacks are invoked.
* Move finishedCallbacks from GrMtlGpu to GrMtlCommandBuffer to ensure
they're really invoked on completion/deletion.
Bug: skia:10530
Change-Id: I9f642342f03f540e46fad62a311c4195be87eab8
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/306936
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
4 files changed