Introducing DemuxerHost::OnMetadata.

media/filters/ffmpeg_demuxer.cc

Index: media/filters/ffmpeg_demuxer.cc
diff --git a/media/filters/ffmpeg_demuxer.cc b/media/filters/ffmpeg_demuxer.cc
index b34d8bc3cb784c81bdae8ca48c4c1ee5d77076b5..348b6a86750a4fdee89fa9197a4393e6e7b579d9 100644
--- a/media/filters/ffmpeg_demuxer.cc
+++ b/media/filters/ffmpeg_demuxer.cc
@@ -1440,6 +1440,7 @@ void FFmpegDemuxer::OnFindStreamInfoDone(const PipelineStatusCB& status_cb,
   if (bitrate_ > 0)
     data_source_->SetBitrate(bitrate_);
 
+  PipelineMetadata metadata;
   // Use a single MediaLogEvent to batch all parameter updates at once; this
   // prevents throttling of events due to the large number of updates here.
   std::unique_ptr<MediaLogEvent> metadata_event =
@@ -1449,6 +1450,7 @@ void FFmpegDemuxer::OnFindStreamInfoDone(const PipelineStatusCB& status_cb,
   metadata_event->params.SetBoolean("found_audio_stream", !!audio_stream);
   if (audio_stream) {
     const AVCodecContext* audio_codec = audio_stream->codec;
+    metadata.has_audio = true;
     metadata_event->params.SetString("audio_codec_name",
                                      GetCodecName(audio_codec));
     metadata_event->params.SetInteger("audio_channels_count",
@@ -1464,6 +1466,9 @@ void FFmpegDemuxer::OnFindStreamInfoDone(const PipelineStatusCB& status_cb,
   metadata_event->params.SetBoolean("found_video_stream", !!video_stream);
   if (video_stream) {
     const AVCodecContext* video_codec = video_stream->codec;
+    metadata.has_video = true;
+    metadata.natural_size = video_->video_decoder_config().natural_size();
+    metadata.video_rotation = video_->video_rotation();
     metadata_event->params.SetString("video_codec_name",
                                      GetCodecName(video_codec));
     metadata_event->params.SetInteger("width", video_codec->width);