Only reinitialize AudioProcessing when needed.

This takes away the burden from the user, resulting in cleaner code.

Review URL: https://webrtc-codereview.appspot.com/941005

git-svn-id: http://webrtc.googlecode.com/svn/trunk@3010 4adac7df-926f-26a2-2b94-8c16560cd09d
4 files changed