Add a ref counted audio bus.

media/base/audio_bus.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_BASE_AUDIO_BUS_H_
 #define MEDIA_BASE_AUDIO_BUS_H_
 
 #include <vector>
 
 #include "base/memory/aligned_memory.h"
+#include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "media/base/media_export.h"
 
 namespace media {
 class AudioParameters;
 
 // Scoped container for "busing" audio channel data around.  Each channel is
 // stored in planar format and guaranteed to be aligned by kChannelAlignment.
 // AudioBus objects can be created normally or via wrapping.  Normally, AudioBus
 // will dice up a contiguous memory block for channel data.  When wrapped,
@@ skipping 82 matching lines @@
   // Scale internal channel values by |volume| >= 0.  If an invalid value
   // is provided, no adjustment is done.
   void Scale(float volume);
 
   // Swaps channels identified by |a| and |b|.  The caller needs to make sure
   // the channels are valid.
   void SwapChannels(int a, int b);
 
   virtual ~AudioBus();
 
- private:
+ protected:
   AudioBus(int channels, int frames);
   AudioBus(int channels, int frames, float* data);
   AudioBus(int frames, const std::vector<float*>& channel_data);
   explicit AudioBus(int channels);
 
+ private:
   // Helper method for building |channel_data_| from a block of memory.  |data|
   // must be at least BlockSize() bytes in size.
   void BuildChannelData(int channels, int aligned_frame, float* data);
 
   // Contiguous block of channel memory.
   scoped_ptr<float, base::AlignedFreeDeleter> data_;
 
   std::vector<float*> channel_data_;
   int frames_;
 
   // Protect SetChannelData() and set_frames() for use by CreateWrapper().
   bool can_set_channel_data_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioBus);
 };
 
+// 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);
+  virtual ~AudioBusRefCounted();
+
+  DISALLOW_COPY_AND_ASSIGN(AudioBusRefCounted);
+};
+
 }  // namespace media
 
 #endif  // MEDIA_BASE_AUDIO_BUS_H_