Add a ref counted audio bus.

For some applications where we need to keep multiple copies of the audio bus around (particularly in STL containers), a scoped_ptr to an audio bus isn't enough. For those rare situations, we're adding a RefCounted version of the AudioBus.

R=dalecurtis@chromium.org
BUG=None.

Review URL: https://codereview.chromium.org/388563005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@282510 0039d316-1c4b-4281-b951-d872f2087c98

media/base/audio_bus.cc

@@ -340,4 +340,15 @@ 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

media/base/audio_bus.h

@@ -8,6 +8,7 @@
 #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"
 
@@ -110,12 +111,13 @@ class MEDIA_EXPORT AudioBus {
 
   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);
@@ -132,6 +134,24 @@ class MEDIA_EXPORT AudioBus {
   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_