Revert of Add mock context and use in ResourceCacheTest. (patchset #4 id:60001 of https://codereview.chromium.org/702083003/)

Reason for revert:
Breaking tests

Original issue's description:
> Add mock context and use in ResourceCacheTest.
>
> BUG=skia:2889
>
> Committed: https://skia.googlesource.com/skia/+/820dd6c335411aad889c1d7e8a857642ecd87e30

TBR=robertphillips@google.com
NOTREECHECKS=true
NOTRY=true
BUG=skia:2889

Review URL: https://codereview.chromium.org/704563004
4 files changed