Add callback for codec format change.

When creating native audio track, a IAudioTrackCallback will be created
systematically. All callbacks will be cached in Threads and protected by
a lock. Whenever there is a callback event from audio HAL, it will
finally trigger callback to native audio track. Currently, there is only
one callback event, which is codec format change.

Bug: 150301890
Test: manual
Change-Id: I32293627ed923b17dd25f11f0ee0a0c35cd7c01f
diff --git a/services/audioflinger/AudioFlinger.h b/services/audioflinger/AudioFlinger.h
index a16fa94..d69b49d 100644
--- a/services/audioflinger/AudioFlinger.h
+++ b/services/audioflinger/AudioFlinger.h
@@ -33,6 +33,7 @@
 #include <sys/types.h>
 #include <limits.h>
 
+#include <android/media/IAudioTrackCallback.h>
 #include <android/os/BnExternalVibrationController.h>
 #include <android-base/macros.h>