Make AudioTrackBufferSizeProvider public.

Was getting "java.lang.IllegalAccessError: Illegal class access" in debug app.

PiperOrigin-RevId: 465562541

RELEASENOTES.md

@@ -12,9 +12,10 @@
     *   Limit parallel download removals to 1 to avoid excessive thread creation
         ([#10458](https://github.com/google/ExoPlayer/issues/10458)).
 *   Audio:
-    *   Adds AudioOffloadListener.onExperimentalOffloadedPlayback for the
+    *   Adds `AudioOffloadListener.onExperimentalOffloadedPlayback` for the
         AudioTrack offload state.
         ([#134](https://github.com/androidx/media/issues/134)).
+    *   Make `AudioTrackBufferSizeProvider` a public interface.
 *   Metadata:
     *   `MetadataRenderer` can now be configured to render metadata as soon as
         they are available. Create an instance with

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/audio/DefaultAudioSink.java

@@ -234,7 +234,7 @@ public final class DefaultAudioSink implements AudioSink {
   }
 
   /** Provides the buffer size to use when creating an {@link AudioTrack}. */
-  interface AudioTrackBufferSizeProvider {
+  public interface AudioTrackBufferSizeProvider {
     /** Default instance. */
     AudioTrackBufferSizeProvider DEFAULT =
         new DefaultAudioTrackBufferSizeProvider.Builder().build();