Reason for revert:
This CL breaks some downstream dependencies (contact me for more info).
Original issue's description:
> Delete unused code httprequest, httpclient, and socketpool.
>
> BUG=webrtc:6424
>
> Committed: https://crrev.com/4a255be3790a040cae2f6182ed70b7dd38c6839e
> Cr-Commit-Position: refs/heads/master@{#14514}
TBR=perkj@webrtc.org,pthatcher@webrtc.org,nisse@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:6424
Review-Url: https://codereview.webrtc.org/2397673002
Cr-Commit-Position: refs/heads/master@{#14518}