Delete unused AudioBusRefCounted structure.

media/base/audio_bus.h

Index: media/base/audio_bus.h
diff --git a/media/base/audio_bus.h b/media/base/audio_bus.h
index 6d381ccac3daa3c9325fb9d4af99259e4cef3825..0632ae1909f7f9f1be55e6369cdcc8b07f12eb0e 100644
--- a/media/base/audio_bus.h
+++ b/media/base/audio_bus.h
@@ -12,7 +12,6 @@
 
 #include "base/macros.h"
 #include "base/memory/aligned_memory.h"
-#include "base/memory/ref_counted.h"
 #include "media/base/media_export.h"
 
 namespace media {
@@ -306,24 +305,6 @@ void AudioBus::CopyConvertFromAudioBusToInterleavedTarget(
   }
 }
 
-// RefCounted version of AudioBus. This is not meant for general use. Only use
-// this when your lifetime requirements make it impossible to use an
-// AudioBus scoped_ptr.
-class MEDIA_EXPORT AudioBusRefCounted
-    : public media::AudioBus,
-      public base::RefCountedThreadSafe<AudioBusRefCounted> {
- public:
-  static scoped_refptr<AudioBusRefCounted> Create(int channels, int frames);
-
- private:
-  friend class base::RefCountedThreadSafe<AudioBusRefCounted>;
-
-  AudioBusRefCounted(int channels, int frames);
-  ~AudioBusRefCounted() override;
-
-  DISALLOW_COPY_AND_ASSIGN(AudioBusRefCounted);
-};
-
 }  // namespace media
 
 #endif  // MEDIA_BASE_AUDIO_BUS_H_