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

webrtc/api/audio_codecs/audio_encoder.cc

 /*
  *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 77 matching lines @@
     int target_audio_bitrate_bps,
     rtc::Optional<int64_t> bwe_period_ms) {}
 
 void AudioEncoder::OnReceivedRtt(int rtt_ms) {}
 
 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