MediaLog: Log selected audio/video decoder name.

media/base/video_decoder.h

Index: media/base/video_decoder.h
diff --git a/media/base/video_decoder.h b/media/base/video_decoder.h
index 89c62dbe4c409f758d9167d9c299c95058c06cfa..52aa86762f1dafbd36fe0d7860a31f69530a73fa 100644
--- a/media/base/video_decoder.h
+++ b/media/base/video_decoder.h
@@ -5,6 +5,8 @@
 #ifndef MEDIA_BASE_VIDEO_DECODER_H_
 #define MEDIA_BASE_VIDEO_DECODER_H_
 
+#include <string>
+
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "media/base/media_export.h"
@@ -46,6 +48,9 @@ class MEDIA_EXPORT VideoDecoder {
   // depends on |this|.
   virtual ~VideoDecoder();
 
+  // Returns the name of the decoder for logging purpose.
+  virtual std::string GetDisplayName() const = 0;
+
   // Initializes a VideoDecoder with the given |config|, executing the
   // |status_cb| upon completion. |output_cb| is called for each output frame
   // decoded by Decode().