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 940e1cc4e0216b93519c33df653dab21eefc1a79..e177acf7713928506162d1d4048213ca469fa778 100644
--- a/webrtc/video/video_send_stream.cc
+++ b/webrtc/video/video_send_stream.cc
@@ -162,6 +162,42 @@ 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 << "input_fps:" << input_frame_rate << ", ";
+  ss << "encode_fps:" << encode_frame_rate << ", ";
+  ss << "encode_ms:" << avg_encode_time_ms << ", ";
+  ss << "encode_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 << "width:" << width << ", ";
+  ss << "height:" << height << ", ";
+  ss << "key:" << frame_counts.key_frames << ", ";
+  ss << "delta:" << frame_counts.delta_frames << ", ";
+  ss << "total_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) {