Revert "Stop using pendingIO in read/writeSurfacePixels"

This reverts commit 76cf552e2854e78a430fb51de040e5eb70387bfe.

Reason for revert: Maybe breaking some bots

Original change's description:
> Stop using pendingIO in read/writeSurfacePixels
> 
> This changes the implementation to always flush for these operations.
> Once partial DAG flushes are implemented this behavior will be better than the old method.
> 
> Change-Id: I1f9edd33dcf5aa15cc5dcdf8f0e06a3b3cd88f48
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/205584
> Reviewed-by: Brian Salomon <bsalomon@google.com>
> Commit-Queue: Robert Phillips <robertphillips@google.com>

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

Change-Id: If3e8cc9a6e92b98f85bc3faf2b99fba7395ec946
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/206067
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
1 file changed