Use AudioTrack::event_type not int in callback

Change-Id: Ifefc708d46874e04fd0d01cb6e2d43b987ee796c
diff --git a/media/libmedia/ToneGenerator.cpp b/media/libmedia/ToneGenerator.cpp
index 9f1b3d6..913a6db 100644
--- a/media/libmedia/ToneGenerator.cpp
+++ b/media/libmedia/ToneGenerator.cpp
@@ -1076,7 +1076,7 @@
 //        returned value: always true.
 //
 ////////////////////////////////////////////////////////////////////////////////
-void ToneGenerator::audioCallback(int event, void* user, void *info) {
+void ToneGenerator::audioCallback(AudioTrack::event_type event, void* user, void *info) {
 
     if (event != AudioTrack::EVENT_MORE_DATA) return;