Revert of Add SkBitmap::readPixels() and reimplement copyTo and SkCanvas::readPixels (https://codereview.chromium.org/388803007/)

Reason for revert:
still failing (randomly?) bench sometimes. need stack dump to diagnose.

Original issue's description:
> Add SkBitmap::readPixels() and reimplement copyTo and SkCanvas::readPixels
> usning it.
>
> Revert "Revert of add readPixels() to SkBitmap (https://codereview.chromium.org/377303002/)"
>
> This reverts commit d08cb905a7cc80d8fb868bbd14fffe1cd68adcce.
>
> TBR=scroggo@google.com
>
> Committed: https://skia.googlesource.com/skia/+/debba5c3d091159149f8a88ab5dcd44dd72e0dc7

R=reed@google.com
TBR=reed@google.com
NOTREECHECKS=true
NOTRY=true

Author: reed@chromium.org

Review URL: https://codereview.chromium.org/382543005
7 files changed