Implement ANA statistics.

webrtc/modules/audio_coding/audio_network_adaptor/audio_network_adaptor_impl.cc

Index: webrtc/modules/audio_coding/audio_network_adaptor/audio_network_adaptor_impl.cc
diff --git a/webrtc/modules/audio_coding/audio_network_adaptor/audio_network_adaptor_impl.cc b/webrtc/modules/audio_coding/audio_network_adaptor/audio_network_adaptor_impl.cc
index 654bc27df55a1d33bd8b2bd91940806b8be48008..07b484e15cce4ad2409d39efd398e05a736d783a 100644
--- a/webrtc/modules/audio_coding/audio_network_adaptor/audio_network_adaptor_impl.cc
+++ b/webrtc/modules/audio_coding/audio_network_adaptor/audio_network_adaptor_impl.cc
@@ -14,6 +14,7 @@
 
 #include "webrtc/rtc_base/logging.h"
 #include "webrtc/rtc_base/timeutils.h"
+#include "webrtc/system_wrappers/include/field_trial.h"
 
 namespace webrtc {
 
@@ -42,6 +43,17 @@ AudioNetworkAdaptorImpl::AudioNetworkAdaptorImpl(
                                    kEventLogMinPacketLossChangeFraction)
               : nullptr) {
   RTC_DCHECK(controller_manager_);
+  // Set the field trial flags to determine if adaptation is enabled.
+  enable_bitrate_adaptation_ =
+      webrtc::field_trial::IsEnabled("WebRTC-Audio-BitrateAdaptation");
+  enable_channel_adaptation_ =
+      webrtc::field_trial::IsEnabled("WebRTC-Audio-ChannelAdaptation");
+  enable_dtx_adaptation_ =
+      webrtc::field_trial::IsEnabled("WebRTC-Audio-DtxAdaptation");
+  enable_fec_adaptation_ =
+      webrtc::field_trial::IsEnabled("WebRTC-Audio-FecAdaptation");
+  enable_frame_length_adaptation_ =
+      webrtc::field_trial::IsEnabled("WebRTC-Audio-FrameLengthAdaptation");
 }
 
 AudioNetworkAdaptorImpl::~AudioNetworkAdaptorImpl() = default;
@@ -118,6 +130,49 @@ AudioEncoderRuntimeConfig AudioNetworkAdaptorImpl::GetEncoderRuntimeConfig() {
        controller_manager_->GetSortedControllers(last_metrics_))
     controller->MakeDecision(&config);
 
+  // Update ANA stats.
+  auto increment_opt = [](rtc::Optional<int>& a) {
+    if (a)
+      (*a)++;
+    else
+      a = rtc::Optional<int>(1);
+  };
+  if (prev_config_) {
+    if (config.bitrate_bps != prev_config_->bitrate_bps) {
+      increment_opt(stats_.ana_bitrate_action_counter);
+    }
+    if (config.enable_dtx != prev_config_->enable_dtx) {
+      increment_opt(stats_.ana_dtx_action_counter);
+    }
+    if (config.enable_fec != prev_config_->enable_fec) {

[alexnarest, 2017/09/04 11:24:02]

In addition I think we want to record the fact FEC controller smoothed the PL or
in case of RPLR-FEC sent RPL instead of RTCP PL in the control group.
I suggest we increment here on FEC enable or PL is greater than 1%.

[ivoc, 2017/09/05 09:01:40]

Another option is to add another stat for uplink packet loss fraction, what do
you think? It could also be implemented as a cumulative stat since the start of
the call, which would make it possible to calculate the average value between
the GetStats() calls. Would that be useful to have?

[alexnarest, 2017/09/05 10:43:27]

Yes, I think it is a good idea

+      increment_opt(stats_.ana_fec_action_counter);
+    }
+    if (config.frame_length_ms != prev_config_->frame_length_ms) {

[alexnarest, 2017/09/05 10:43:27]

It would be helpful to report inc/dec counters rather than the general change
counter.

+      increment_opt(stats_.ana_frame_length_action_counter);
+    }
+    if (config.num_channels != prev_config_->num_channels) {
+      increment_opt(stats_.ana_channel_action_counter);
+    }
+  }
+  prev_config_ = rtc::Optional<AudioEncoderRuntimeConfig>(config);
+
+  // Prevent certain controllers from taking action (determined by field trials)
+  if (!enable_bitrate_adaptation_ && config.bitrate_bps) {
+    config.bitrate_bps = rtc::Optional<int>();
+  }
+  if (!enable_dtx_adaptation_ && config.enable_dtx) {
+    config.enable_dtx = rtc::Optional<bool>();
+  }
+  if (!enable_fec_adaptation_ && config.enable_fec) {

[alexnarest, 2017/09/04 11:24:01]

In addition to enable_fec we want to prevent PL smoothing and RPL reporting in
case of RPLR-FEC

[ivoc, 2017/09/05 09:01:40]

Good point, done.

+    config.enable_fec = rtc::Optional<bool>();
+  }
+  if (!enable_frame_length_adaptation_ && config.frame_length_ms) {
+    config.frame_length_ms = rtc::Optional<int>();
+  }
+  if (!enable_channel_adaptation_ && config.num_channels) {
+    config.num_channels = rtc::Optional<size_t>();
+  }
+
   if (debug_dump_writer_)
     debug_dump_writer_->DumpEncoderRuntimeConfig(config, rtc::TimeMillis());
 
@@ -137,8 +192,7 @@ void AudioNetworkAdaptorImpl::StopDebugDump() {
 
 AudioNetworkAdaptorImpl::AudioNetworkAdaptorStats
 AudioNetworkAdaptorImpl::GetStats() const {
-  // TODO(ivoc): Actually implement the stat.
-  return AudioNetworkAdaptorStats();
+  return stats_;
 }
 
 void AudioNetworkAdaptorImpl::DumpNetworkMetrics() {