Revert "Use SkImage to manage mip map cache purging, not Bitmap/PixelRef"

This reverts commit 087c91767049dab810bf808519b31d7bdbcb86d1.

Reason for revert: ASAN reporting memory leak.

Original change's description:
> Use SkImage to manage mip map cache purging, not Bitmap/PixelRef
> 
> Lazy and GPU images manage the notification themselves, but raster
> images now forward the notification request to the pixelRef.
> 
> Bug: skia:
> Change-Id: I93e0ebd3749e3f7dbd506466299fde8923982435
> Reviewed-on: https://skia-review.googlesource.com/c/161830
> Commit-Queue: Mike Klein <mtklein@google.com>
> Reviewed-by: Mike Klein <mtklein@google.com>

TBR=mtklein@google.com,brianosman@google.com,reed@google.com

Change-Id: I355b8caeaae3096e52f5fd2359f4ad39cddaa383
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:
Reviewed-on: https://skia-review.googlesource.com/c/162034
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
6 files changed