Revert of small CL to experiment with 'disabling' memory mapping (patchset #1 id:1 of https://codereview.chromium.org/1160003004/)

Reason for revert:
experiment complete

Original issue's description:
> small CL to experiment with 'disabling' memory mapping
>
> TBR=bsalomon@google.com
> BUG=skia:
>
> Committed: https://skia.googlesource.com/skia/+/2e48e1514396b363ecd19372eab637b11bfb8a82

TBR=robertphillips@google.com,joshualitt@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review URL: https://codereview.chromium.org/1159133004
1 file changed