Reason for revert:
Intend to fix perf failures and reland.
Original issue's description:
> Revert of Use RtxReceiveStream. (patchset #5 id:80001 of https://codereview.webrtc.org/3008773002/ )
>
> Reason for revert:
> A few perf tests broken, including
>
> RampUpTest.UpDownUpAbsSendTimeSimulcastRedRtx
> RampUpTest.UpDownUpTransportSequenceNumberRtx
> RampUpTest.UpDownUpTransportSequenceNumberPacketLoss
>
>
> Original issue's description:
> > Use RtxReceiveStream.
> >
> > This also has the beneficial side-effect that when a media stream
> > which is protected by FlexFEC receives an RTX retransmission, the
> > retransmitted media packet is passed into the FlexFEC machinery,
> > which should improve its ability to recover packets via FEC.
> >
> > BUG=webrtc:7135
> >
> > Review-Url: https://codereview.webrtc.org/3008773002
> > Cr-Commit-Position: refs/heads/master@{#19649}
> > Committed: 5c0f6c62ea
>
> TBR=brandtr@webrtc.org,danilchap@webrtc.org,stefan@webrtc.org,magjed@webrtc.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=webrtc:7135
>
> Review-Url: https://codereview.webrtc.org/3010983002
> Cr-Commit-Position: refs/heads/master@{#19653}
> Committed: 3c39c0137aTBR=brandtr@webrtc.org,danilchap@webrtc.org,stefan@webrtc.org,magjed@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
BUG=webrtc:7135
Review-Url: https://codereview.webrtc.org/3006063002
Cr-Commit-Position: refs/heads/master@{#19715}
35713eaf56