Fix incorrect includes of AudioTrack.h

Remove unnecessary includes of AudioTrack.h.
Use forward declaration of class names in preference to #include when possible.

Change-Id: I12982811fa75c2c7695d8bbfa595a7aaec047dc0
diff --git a/media/libmediaplayerservice/MediaPlayerService.h b/media/libmediaplayerservice/MediaPlayerService.h
index 6b68b87..fa71d11 100644
--- a/media/libmediaplayerservice/MediaPlayerService.h
+++ b/media/libmediaplayerservice/MediaPlayerService.h
@@ -34,6 +34,7 @@
 
 namespace android {
 
+class AudioTrack;
 class IMediaRecorder;
 class IMediaMetadataRetriever;
 class IOMX;
diff --git a/media/libmediaplayerservice/MediaRecorderClient.cpp b/media/libmediaplayerservice/MediaRecorderClient.cpp
index d219fc2..beda945 100644
--- a/media/libmediaplayerservice/MediaRecorderClient.cpp
+++ b/media/libmediaplayerservice/MediaRecorderClient.cpp
@@ -33,8 +33,6 @@
 
 #include <utils/String16.h>
 
-#include <media/AudioTrack.h>
-
 #include <system/audio.h>
 
 #include "MediaRecorderClient.h"
diff --git a/media/libmediaplayerservice/MidiFile.h b/media/libmediaplayerservice/MidiFile.h
index dfe4318..f6f8f7b 100644
--- a/media/libmediaplayerservice/MidiFile.h
+++ b/media/libmediaplayerservice/MidiFile.h
@@ -19,7 +19,6 @@
 #define ANDROID_MIDIFILE_H
 
 #include <media/MediaPlayerInterface.h>
-#include <media/AudioTrack.h>
 #include <libsonivox/eas.h>
 
 namespace android {