Annotating the rest of AudioCodingModuleImpl

A few extra locks had to be acquired as a result of the annotation.

BUG=3401
R=kwiberg@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/15819004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6524 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/audio_coding/main/interface/audio_coding_module.h

@@ -330,6 +330,7 @@ class AudioCodingModule: public Module {
   //   -1 if error occurred in setting the bandwidth,
   //    0 bandwidth is set successfully.
   //
+  // TODO(henrik.lundin) Unused. Remove?
   virtual int32_t SetReceivedEstimatedBandwidth(
       const int32_t bw) = 0;