Revert "Revert "Refactor AudioTrack callback to Interface""

This reverts commit f13b98aac7921d6ef707940daf82cc4334f5e790.

Change-Id: I67dc284307419737eeb055db851751455abf103d
diff --git a/media/libaaudio/src/legacy/AudioStreamTrack.cpp b/media/libaaudio/src/legacy/AudioStreamTrack.cpp
index b512b48..fe84ec5 100644
--- a/media/libaaudio/src/legacy/AudioStreamTrack.cpp
+++ b/media/libaaudio/src/legacy/AudioStreamTrack.cpp
@@ -103,7 +103,7 @@
             : getFormat();
 
     // Setup the callback if there is one.
-    AudioTrack::callback_t callback = nullptr;
+    AudioTrack::legacy_callback_t callback = nullptr;
     void *callbackData = nullptr;
     // Note that TRANSFER_SYNC does not allow FAST track
     AudioTrack::transfer_type streamTransferType = AudioTrack::transfer_type::TRANSFER_SYNC;