SendStreamAudio gets called by SendStreamData which can be called
on the state machine thread since bug 794426 was fixed.
At the same time PlayFromAudioQueuec can no longer guarantee that
mAudioCaptured is false. It could be true and we're waiting for
the audio thread to shut down. We can just remove that assertion;
the logic in SendStreamData guarantees that we don't try to pass
audio to MediaStreams until the audio thread has actually stopped.
--HG--
extra : rebase_source : 431b4af63710ef13a57f7560aeec553b8aae6139
