MediaLog: Log selected audio/video decoder name.

media/base/audio_decoder.h

Index: media/base/audio_decoder.h
diff --git a/media/base/audio_decoder.h b/media/base/audio_decoder.h
index 779e5ef502654644d6252d3ca0f3f6c5237689fc..44e79a4d5b31c0fd976484c2281cce60e1eeca17 100644
--- a/media/base/audio_decoder.h
+++ b/media/base/audio_decoder.h
@@ -5,6 +5,8 @@
 #ifndef MEDIA_BASE_AUDIO_DECODER_H_
 #define MEDIA_BASE_AUDIO_DECODER_H_
 
+#include <string>
+
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "media/base/audio_decoder_config.h"
@@ -47,6 +49,9 @@ class MEDIA_EXPORT AudioDecoder {
   // depends on |this|.
   virtual ~AudioDecoder();
 
+  // Returns the name of the decoder for logging purpose.
+  virtual std::string GetDisplayName() const = 0;
+
   // Initializes an AudioDecoder with the given DemuxerStream, executing the
   // callback upon completion.
   //  |statistics_cb| is used to update global pipeline statistics.