Add periodic logging of video stats.

webrtc/video/video_send_stream.cc

Index: webrtc/video/video_send_stream.cc
diff --git a/webrtc/video/video_send_stream.cc b/webrtc/video/video_send_stream.cc
index 3e95cb02956fc8d350703ca617704322fe513ba0..619aaffa87c2f1fe9c30516e52c484252303c525 100644
--- a/webrtc/video/video_send_stream.cc
+++ b/webrtc/video/video_send_stream.cc
@@ -160,6 +160,42 @@ std::string VideoSendStream::Config::ToString() const {
   return ss.str();
 }
 
+std::string VideoSendStream::Stats::ToString(int64_t time_ms) const {
+  std::stringstream ss;
+  ss << "VideoSendStream stats:" << time_ms << ",{";
+  ss << "[in_fps:" << input_frame_rate << "],";
+  ss << "[enc_fps:" << encode_frame_rate << "],";
+  ss << "[enc_ms:" << avg_encode_time_ms << "],";
+  ss << "[enc_usage_perc:" << encode_usage_percent << "],";
+  ss << "[target_bps:" << target_media_bitrate_bps << "],";
+  ss << "[media_bps:" << media_bitrate_bps << "],";
+  ss << "[suspended:" << (suspended ? "true" : "false") << "],";
+  ss << "[bw_adapted:" << (bw_limited_resolution ? "true" : "false") << "]";
+  ss << '}';
+  for (const auto& substream : substreams) {
+    ss << " {ssrc:" << substream.first << ",";
+    ss << substream.second.ToString();
+    ss << '}';
+  }
+  return ss.str();
+}
+
+std::string VideoSendStream::StreamStats::ToString() const {
+  std::stringstream ss;
+  ss << "[w:" << width << "],";
+  ss << "[h:" << height << "],";
+  ss << "[key:" << frame_counts.key_frames << "],";
+  ss << "[delta:" << frame_counts.delta_frames << "],";
+  ss << "[tot_bps:" << total_bitrate_bps << "],";
+  ss << "[retransmit_bps:" << retransmit_bitrate_bps << "],";
+  ss << "[avg_delay_ms:" << avg_delay_ms << "],";
+  ss << "[max_delay_ms:" << max_delay_ms << "],";
+  ss << "[nack:" << rtcp_packet_type_counts.nack_packets << "],";
+  ss << "[fir:" << rtcp_packet_type_counts.fir_packets << "],";
+  ss << "[pli:" << rtcp_packet_type_counts.pli_packets << "]";
+  return ss.str();
+}
+
 namespace {
 
 VideoCodecType PayloadNameToCodecType(const std::string& payload_name) {