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

webrtc/api/audio_codecs/audio_encoder.cc

Index: webrtc/api/audio_codecs/audio_encoder.cc
diff --git a/webrtc/api/audio_codecs/audio_encoder.cc b/webrtc/api/audio_codecs/audio_encoder.cc
index 3ee371f1cee7f4b5d5390bd8c3340d7d1abd42a3..1e8bfee4da641c7e78026ead435546d923f13c4d 100644
--- a/webrtc/api/audio_codecs/audio_encoder.cc
+++ b/webrtc/api/audio_codecs/audio_encoder.cc
@@ -95,4 +95,8 @@ void AudioEncoder::OnReceivedOverhead(size_t overhead_bytes_per_packet) {}
 void AudioEncoder::SetReceiverFrameLengthRange(int min_frame_length_ms,
                                                int max_frame_length_ms) {}
 
+ANAStats AudioEncoder::GetANAStats() const {
+  return ANAStats();
+}
+
 }  // namespace webrtc