This is a reland of 8b40ac35b2
Original change's description:
> Reintroduce deinstantiate lazy proxy types and use for promise images.
>
> This reverts a fraction of b2c5dae65d to
> restore the deinstantiate lazy proxy type, supporting implementation,
> and tests.
>
> Use them for promise images to avoid thread safety issues for promise
> image resources. Makes promise image instantiation callbacks do a thread
> safe unref of their fulfilled GrTexture in GrResourceCache. The
> GrResourceCache mechanism for receiving unref messages is extended to
> allow multiple pending unrefs. All this is new.
>
>
> Bug: skia:8800
> Change-Id: I7b1d4fea13c053b6fbbd39c0c6eaf567b8bf81f1
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/199002
> Reviewed-by: Brian Salomon <bsalomon@google.com>
> Reviewed-by: Robert Phillips <robertphillips@google.com>
> Commit-Queue: Brian Salomon <bsalomon@google.com>
Bug: skia:8800
Change-Id: Ib939fc5c19edf0c6b965c9f6adf0afedd4267703
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/201220
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
876a017e53