Add new ANA stats to the old GetStats() to count the number of actions taken by each controller.

This CL only wires up the new stats but does not set the values yet. This will be added in a follow-up CL.

BUG=webrtc:8127

Review-Url: https://codereview.webrtc.org/3011623002
Cr-Commit-Position: refs/heads/master@{#19751}

webrtc/modules/audio_coding/include/audio_coding_module.h

@@ -823,6 +823,8 @@ class AudioCodingModule {
 
   virtual void GetDecodingCallStatistics(
       AudioDecodingCallStats* call_stats) const = 0;
+
+  virtual ANAStats GetANAStats() const = 0;
 };
 
 }  // namespace webrtc