Check for single owner and abandoned context in createMipMapProxyFromBitmap

Bug: skia:
Change-Id: I64d4844300be3e49673f919f4e85dbff7cd4bb92
Reviewed-on: https://skia-review.googlesource.com/c/190440
Commit-Queue: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
Auto-Submit: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>