Revert of Remove a scoped_refptr<>::swap overload

media/filters/ffmpeg_audio_decoder.cc

Index: media/filters/ffmpeg_audio_decoder.cc
diff --git a/media/filters/ffmpeg_audio_decoder.cc b/media/filters/ffmpeg_audio_decoder.cc
index 06233eaa7d141c033ac0c80a7574defee61d04ba..e3560ff1b8bcf9d359f2a7c0ab06147b8e6b4e3f 100644
--- a/media/filters/ffmpeg_audio_decoder.cc
+++ b/media/filters/ffmpeg_audio_decoder.cc
@@ -45,8 +45,8 @@
 // Called by FFmpeg's allocation routine to free a buffer. |opaque| is the
 // AudioBuffer allocated, so unref it.
 static void ReleaseAudioBufferImpl(void* opaque, uint8_t* data) {
-  if (opaque)
-    static_cast<AudioBuffer*>(opaque)->Release();
+  scoped_refptr<AudioBuffer> buffer;
+  buffer.swap(reinterpret_cast<AudioBuffer**>(&opaque));
 }
 
 // Called by FFmpeg's allocation routine to allocate a buffer. Uses
@@ -124,8 +124,8 @@
 
   // Now create an AVBufferRef for the data just allocated. It will own the
   // reference to the AudioBuffer object.
-  AudioBuffer* opaque = buffer.get();
-  opaque->AddRef();
+  void* opaque = NULL;
+  buffer.swap(reinterpret_cast<AudioBuffer**>(&opaque));
   frame->buf[0] = av_buffer_create(
       frame->data[0], buffer_size_in_bytes, ReleaseAudioBufferImpl, opaque, 0);
   return 0;