This should hopefully fix static initializer warnings when rolling webrtc in Chromium. TEST=logging_unittest succeeds with enable_tracing==1 and fails appropriately with enable_tracing==0. Review URL: https://webrtc-codereview.appspot.com/939026 git-svn-id: http://webrtc.googlecode.com/svn/trunk@3159 4adac7df-926f-26a2-2b94-8c16560cd09d