Revert "Use AudioTrack::event_type not int in callback"

This reverts commit 2225e4b7049fa3fb9d39a068b8268b63c952d7c1
diff --git a/include/media/ToneGenerator.h b/include/media/ToneGenerator.h
index 9da069c..1ad1f26 100644
--- a/include/media/ToneGenerator.h
+++ b/include/media/ToneGenerator.h
@@ -270,7 +270,7 @@
     unsigned int mProcessSize;  // Size of audio blocks generated at a time by audioCallback() (in PCM frames).
 
     bool initAudioTrack();
-    static void audioCallback(AudioTrack::event_type event, void* user, void *info);
+    static void audioCallback(int event, void* user, void *info);
     bool prepareWave();
     unsigned int numWaves(unsigned int segmentIdx);
     void clearWaveGens();