ARC cleanup and memory leak fix.

After looking at it again, we don't need autoreleasepool blocks in
as many places as I originally thought, so this removes those. In
doing so I found that we were leaking SamplerState and DepthStencilState.

Bug: skia:8245
Change-Id: Ibb53b1d4c3f077b8c62f9bfdf39c0f8c9a1b9b9c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/215160
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
26 files changed