Revert "Remove deferred proxy machinery"

This reverts commit a3987cc5873c9bce758fa3843bb801c95d282bbd.

Reason for revert: Keeping it

Original change's description:
> Remove deferred proxy machinery
>
> These aren't used any more in favor of lazy proxies.
>
> Bug: skia:11288
> Change-Id: I992e1a3dd343e0ebc7f3a4f18c0054453dfebbaf
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/366896
> Commit-Queue: Adlai Holler <adlai@google.com>
> Reviewed-by: Brian Salomon <bsalomon@google.com>

TBR=bsalomon@google.com,robertphillips@google.com,adlai@google.com

Bug: skia:11288
Change-Id: Iafa9ed18a772e451349dfad61ee462df963028be
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/368376
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Adlai Holler <adlai@google.com>
Commit-Queue: Adlai Holler <adlai@google.com>
22 files changed