Emit Media Source codec names as media_log events.

media/base/audio_decoder_config.cc

Index: media/base/audio_decoder_config.cc
diff --git a/media/base/audio_decoder_config.cc b/media/base/audio_decoder_config.cc
index 06a1643f0a1ae4c2cf1b869dbf87fd9a02c42024..d77d8da565a3828cd08ab6f627d482ae7d8f9413 100644
--- a/media/base/audio_decoder_config.cc
+++ b/media/base/audio_decoder_config.cc
@@ -108,7 +108,7 @@ bool AudioDecoderConfig::Matches(const AudioDecoderConfig& config) const {
 
 std::string AudioDecoderConfig::AsHumanReadableString() const {
   std::ostringstream s;
-  s << "codec: " << codec()
+  s << "codec: " << GetHumanReadableCodecName()
     << " bytes_per_channel: " << bytes_per_channel()
     << " channel_layout: " << channel_layout()
     << " samples_per_second: " << samples_per_second()
@@ -121,4 +121,38 @@ std::string AudioDecoderConfig::AsHumanReadableString() const {
   return s.str();
 }
 
+// These names come from src/third_party/ffmpeg/libavcodec/codec_desc.c
+std::string AudioDecoderConfig::GetHumanReadableCodecName() const {
+  switch (codec()) {
+    case kUnknownAudioCodec:
+      return "unknown";
+    case kCodecAAC:
+      return "aac";
+    case kCodecMP3:
+      return "mp3";
+    case kCodecPCM:
+    case kCodecPCM_S16BE:
+    case kCodecPCM_S24BE:
+      return "pcm";
+    case kCodecVorbis:
+      return "vorbis";
+    case kCodecFLAC:
+      return "flac";
+    case kCodecAMR_NB:
+      return "amr_nb";
+    case kCodecAMR_WB:
+      return "amr_wb";
+    case kCodecGSM_MS:
+      return "gsm_ms";
+    case kCodecPCM_ALAW:
+      return "pcm_alaw";
+    case kCodecPCM_MULAW:
+      return "pcm_mulaw";
+    case kCodecOpus:
+      return "opus";
+  }
+  NOTREACHED();
+  return "";
+}
+
 }  // namespace media