Emit Media Source stream type and codecs to chrome://media-internals.

media/filters/stream_parser_factory.cc

Index: media/filters/stream_parser_factory.cc
diff --git a/media/filters/stream_parser_factory.cc b/media/filters/stream_parser_factory.cc
index 5e1ef33168a7754963b337dbccff7fd640b6c477..2c1a34308f5d3f4f594bf7a3206e34367a9029ba 100644
--- a/media/filters/stream_parser_factory.cc
+++ b/media/filters/stream_parser_factory.cc
@@ -376,6 +376,7 @@ bool StreamParserFactory::IsTypeSupported(
 scoped_ptr<StreamParser> StreamParserFactory::Create(
     const std::string& type,
     const std::vector<std::string>& codecs,
+    const scoped_refptr<MediaLog>& media_log,
     const LogCB& log_cb,
     bool* has_audio,
     bool* has_video) {
@@ -395,6 +396,10 @@ scoped_ptr<StreamParser> StreamParserFactory::Create(
     *has_audio = !audio_codecs.empty();
     *has_video = !video_codecs.empty();
 
+    media_log->SetStringProperty("media_source_type", type);
+    media_log->SetStringProperty("media_source_codecs",
+                                 JoinString(codecs, ','));
+
     // Log the number of codecs specified, as well as the details on each one.
     UMA_HISTOGRAM_COUNTS_100("Media.MSE.NumberOfTracks", codecs.size());
     for (size_t i = 0; i < audio_codecs.size(); ++i) {