Revert of Implement THROTTLED priority semantics. (patchset #54 id:1090001 of https://codereview.chromium.org/2130493002/ )

Reason for revert:
Crash on Android Cronet Lollipop bots.

Original issue's description:
> Implement THROTTLED priority semantics.
>
> BUG=600839
> R=mmenke@chromium.org
>
> Committed: https://crrev.com/a3ea24ae1987d24b536859dad3d18537dd917242
> Cr-Commit-Position: refs/heads/master@{#432558}

TBR=mmenke@chromium.org,csharrison@chromium.org,rsleevi@chromium.org,yfriedman@chromium.org,tedchoc@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=600839

Review-Url: https://codereview.chromium.org/2511493002
Cr-Commit-Position: refs/heads/master@{#432585}
14 files changed