Revert of Implement AudioReceiveStream::GetStats().

Revert of Implement AudioReceiveStream::GetStats(). (patchset #19 id:360001 of https://codereview.webrtc.org/1390753002/ )

Reason for revert:
webrtc_perf_tests started failing on Win32 Release, Mac32 Release and Linux64 Release (all running large tests). These were not caught by try bots.

Original issue's description:
> Implement AudioReceiveStream::GetStats().
>
> R=tommi@webrtc.org
> TBR=hta@webrtc.org
> BUG=webrtc:4690
>
> Committed: https://chromium.googlesource.com/external/webrtc/+/a457752f4afc496ed7f4d6b584b08d8635f18cc0

TBR=tommi@webrtc.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:4690
Committed: https://crrev.com/43e83d44f01683fbd304e37d47d2f6db0d52660d
Cr-Commit-Position: refs/heads/master@{#10340}

[the sun, 2015-10-20 13:40:47]

Created Revert of Implement AudioReceiveStream::GetStats().

[commit-bot: I haz the power, 2015-10-20 13:40:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1411083006/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1411083006/1

[commit-bot: I haz the power, 2015-10-20 13:41:05]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-20 13:41:11]

Patchset 1 (id:??) landed as
https://crrev.com/43e83d44f01683fbd304e37d47d2f6db0d52660d
Cr-Commit-Position: refs/heads/master@{#10340}