Add experimental noise suppression dummy API.

Add this flag to the voe_cmd_test.

R=andrew@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/3879004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@5134 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/audio_processing/include/audio_processing.h

@@ -155,6 +155,9 @@ class AudioProcessing : public Module {
   // ensures the options are applied immediately.
   virtual void SetExtraOptions(const Config& config) = 0;
 
+  virtual int EnableExperimentalNs(bool enable) = 0;
+  virtual bool experimental_ns_enabled() const = 0;
+
   // Sets the sample |rate| in Hz for both the primary and reverse audio
   // streams. 8000, 16000 or 32000 Hz are permitted.
   virtual int set_sample_rate_hz(int rate) = 0;