Revert of Restructure flushing relationship between GrContext, GrDrawingManager, and GrResourceCache. (patchset #4 id:60001 of https://codereview.chromium.org/2307053002/ )

Reason for revert:
Causing assertions on bots

Original issue's description:
> Restructure flushing relationship between GrContext, GrDrawingManager, and GrResourceCache.
>
> Consolidates all flush actions into GrDrawingManager and makes GrContext::flush a passthrough.
>
> Removes the unused and untested discard flush variation.
>
> Replaces the indirect overbudget callback mechanism of GrResourceCache with a flag set by resource cache when it wants to flush that is checked after each draw by GrDrawContext.
>
> Modifies GrResourceCache::notifyFlushOccurred() to take a param indicating whether it triggered the
> flush that just occurred.
>
> GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2307053002
>
> Committed: https://skia.googlesource.com/skia/+/1dbb207babecdae8f1f74ed9d9900c73064df744

TBR=robertphillips@google.com
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review-Url: https://codereview.chromium.org/2312123003
9 files changed