Emit Media Source codec names as media_log events.

media/base/video_decoder_config.cc

Index: media/base/video_decoder_config.cc
diff --git a/media/base/video_decoder_config.cc b/media/base/video_decoder_config.cc
index d2b6e410103e4a066c9b971a9376a30d3caa48c9..27fe9f59b9f08dc780081fd650928fd0dfcc09ff 100644
--- a/media/base/video_decoder_config.cc
+++ b/media/base/video_decoder_config.cc
@@ -113,7 +113,7 @@ bool VideoDecoderConfig::Matches(const VideoDecoderConfig& config) const {
 
 std::string VideoDecoderConfig::AsHumanReadableString() const {
   std::ostringstream s;
-  s << "codec: " << codec()
+  s << "codec: " << GetHumanReadableCodecName()
     << " format: " << format()
     << " profile: " << profile()
     << " coded size: [" << coded_size().width()
@@ -129,6 +129,30 @@ std::string VideoDecoderConfig::AsHumanReadableString() const {
   return s.str();
 }
 
+// The names come from src/third_party/ffmpeg/libavcodec/codec_desc.c
+std::string VideoDecoderConfig::GetHumanReadableCodecName() const {
+  switch (codec()) {
+    case kUnknownVideoCodec:
+      return "unknown";
+    case kCodecH264:
+      return "h264";
+    case kCodecVC1:
+      return "vc1";
+    case kCodecMPEG2:
+      return "mpeg2video";
+    case kCodecMPEG4:
+      return "mpeg4";
+    case kCodecTheora:
+      return "theora";
+    case kCodecVP8:
+      return "vp8";
+    case kCodecVP9:
+      return "vp9";
+  }
+  NOTREACHED();
+  return "";
+}
+
 VideoCodec VideoDecoderConfig::codec() const {
   return codec_;
 }