Revert 255158 "Avoid hitting the thread check when WebRtcAudioRe..."

This needs to be reverted because it's causing complete audio loss in apps
using WebRTC.

BUG=351895,264611

> Avoid hitting the thread check when WebRtcAudioRenderer is going away.
> 
> We need to reset the render_thread_checker and render_converter_ when the WebRtcAudioRenderer is going away.
> 
> NOTRY=true
> 
> BUG=264611
> TEST=manual test webrtc with --enable-audio-track-processor
> 
> Review URL: https://codereview.chromium.org/178153007

TBR=xians@chromium.org

Review URL: https://codereview.chromium.org/195763008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256664 0039d316-1c4b-4281-b951-d872f2087c98
5 files changed