Delete unused AudioBusRefCounted structure.

media/base/audio_bus.cc

Index: media/base/audio_bus.cc
diff --git a/media/base/audio_bus.cc b/media/base/audio_bus.cc
index d261e87f8dc9f26ae29338b874343eebf728f275..31e9e4f49cc215448cd95b60858d584a2b651370 100644
--- a/media/base/audio_bus.cc
+++ b/media/base/audio_bus.cc
@@ -344,15 +344,4 @@ void AudioBus::SwapChannels(int a, int b) {
   std::swap(channel_data_[a], channel_data_[b]);
 }
 
-scoped_refptr<AudioBusRefCounted> AudioBusRefCounted::Create(
-    int channels, int frames) {
-  return scoped_refptr<AudioBusRefCounted>(
-      new AudioBusRefCounted(channels, frames));
-}
-
-AudioBusRefCounted::AudioBusRefCounted(int channels, int frames)
-    : AudioBus(channels, frames) {}
-
-AudioBusRefCounted::~AudioBusRefCounted() {}
-
 }  // namespace media