Added a system delay test class. Noticed I don't need the ApmTest class at all, which simplified the implementation. Start at patch set 3. The others are not complete. BUG=None TEST= Review URL: https://webrtc-codereview.appspot.com/475003 git-svn-id: http://webrtc.googlecode.com/svn/trunk@2014 4adac7df-926f-26a2-2b94-8c16560cd09d