Convert MediaLog from being ref counted to owned by WebMediaPlayer.

media/renderers/audio_renderer_impl.h

Index: media/renderers/audio_renderer_impl.h
diff --git a/media/renderers/audio_renderer_impl.h b/media/renderers/audio_renderer_impl.h
index 93d19898dc9f74a2d5e0876ac322c2ea672d27b3..8b8273cb93d574bd6170eca752121b6379bf9e8e 100644
--- a/media/renderers/audio_renderer_impl.h
+++ b/media/renderers/audio_renderer_impl.h
@@ -64,7 +64,7 @@ class MEDIA_EXPORT AudioRendererImpl
       const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
       AudioRendererSink* sink,
       const CreateAudioDecodersCB& create_audio_decoders_cb,
-      const scoped_refptr<MediaLog>& media_log);
+      MediaLog* media_log);
   ~AudioRendererImpl() override;
 
   // TimeSource implementation.
@@ -217,7 +217,7 @@ class MEDIA_EXPORT AudioRendererImpl
 
   std::unique_ptr<AudioBufferStream> audio_buffer_stream_;
 
-  scoped_refptr<MediaLog> media_log_;
+  MediaLog* media_log_;
 
   // Cached copy of hardware params from |sink_|.
   AudioParameters audio_parameters_;