Remove SetNotAlive method from the thread class.

Also cleaning up methods with the same name in other classes that are derived from the above method.

R=perkj@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/41759004

Cr-Commit-Position: refs/heads/master@{#8242}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8242 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/utility/source/process_thread_impl.cc

@@ -65,8 +65,6 @@ int32_t ProcessThreadImpl::Stop()
     _critSectModules->Enter();
     if(_thread)
     {
-        _thread->SetNotAlive();
-
         ThreadWrapper* thread = _thread;
         _thread = NULL;