Introduce AudioBufferMemoryPool to avoid thrashing on audio buffers.

media/filters/android/media_codec_audio_decoder.h

Index: media/filters/android/media_codec_audio_decoder.h
diff --git a/media/filters/android/media_codec_audio_decoder.h b/media/filters/android/media_codec_audio_decoder.h
index e845be6103529641a2f50b6afd57d53f1a3e49da..e5a8958f147938ee7c44e54647a213f278b0c1d2 100644
--- a/media/filters/android/media_codec_audio_decoder.h
+++ b/media/filters/android/media_codec_audio_decoder.h
@@ -16,6 +16,7 @@
 #include "base/timer/timer.h"
 #include "media/base/android/media_codec_loop.h"
 #include "media/base/android/media_drm_bridge_cdm_context.h"
+#include "media/base/audio_buffer.h"
 #include "media/base/audio_decoder.h"
 #include "media/base/audio_decoder_config.h"
 #include "media/base/media_export.h"
@@ -192,6 +193,9 @@ class MEDIA_EXPORT MediaCodecAudioDecoder : public AudioDecoder,
   // registration id is used for this.
   int cdm_registration_id_;
 
+  // Pool which helps avoid thrashing memory when returning audio buffers.
+  scoped_refptr<AudioBufferMemoryPool> pool_;
+
   // The MediaCrypto object is used in the MediaCodec.configure() in case of
   // an encrypted stream.
   media::MediaDrmBridgeCdmContext::JavaObjectPtr media_crypto_;