Remove legacy async read pixels APIs.

Chrome is now using the newer version.

Bug: skia:8962
Change-Id: I8c38bde63e1e032281d19b0cc7cb8cf301061a9e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/251198
Commit-Queue: Greg Daniel <egdaniel@google.com>
Auto-Submit: Brian Salomon <bsalomon@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
4 files changed