This is the same change as already made for Windows:
https://webrtc-codereview.appspot.com/37069004/
* Remove "dead" and "alive" variables.
* Remove critical section
* Remove implementation of SetNotAlive()
* Always set thread name
* Add thread checks for correct usage.
* Changed AudioDeviceMac to create/start/stop/delete thread objects for playout and recording, inside the respective start and stop method. The reason for this is because the AudioDeviceMac instance is currently being created on one thread and the above Start/Stop methods are being called on a different thread. So, my change makes creation, start/stop, deletion of the thread objects always happen on the same thread.
I'm making CurrentThreadId() in rtc_base_approved more visible so that it can be used from there instead of inside webrtc. Down the line we will have more thread concepts in rtc_base_approved, so I put a TODO for myself to move this functionality to there once we do.
R=henrika@webrtc.org
Review URL: https://webrtc-codereview.appspot.com/40599004
Cr-Commit-Position: refs/heads/master@{#8235}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8235 4adac7df-926f-26a2-2b94-8c16560cd09d
