Checks must be made with "!= 0", not "== -1". Additionally: * Clean up the function calling into AudioProcessing. * Remove the unused _noiseWarning. * Make the other warnings bool. BUG=chromium:178040 Review URL: https://webrtc-codereview.appspot.com/1147004 git-svn-id: http://webrtc.googlecode.com/svn/trunk@3590 4adac7df-926f-26a2-2b94-8c16560cd09d