Convert MediaLog from being ref counted to owned by WebMediaPlayer.

media/filters/decrypting_audio_decoder.h

Index: media/filters/decrypting_audio_decoder.h
diff --git a/media/filters/decrypting_audio_decoder.h b/media/filters/decrypting_audio_decoder.h
index 061ef1db46299b0b40e426694b7d804ceb8880db..5d807999618d8fa874864240de357f912e29c298 100644
--- a/media/filters/decrypting_audio_decoder.h
+++ b/media/filters/decrypting_audio_decoder.h
@@ -36,7 +36,7 @@ class MEDIA_EXPORT DecryptingAudioDecoder : public AudioDecoder {
  public:
   DecryptingAudioDecoder(
       const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
-      const scoped_refptr<MediaLog>& media_log,
+      MediaLog* media_log,
       const base::Closure& waiting_for_decryption_key_cb);
   ~DecryptingAudioDecoder() override;
 
@@ -90,7 +90,7 @@ class MEDIA_EXPORT DecryptingAudioDecoder : public AudioDecoder {
 
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
 
-  scoped_refptr<MediaLog> media_log_;
+  MediaLog* media_log_;
 
   State state_;