Get service by value instead of reference

to prevent a cleared service binder from being used.

Bug: 26040840
Change-Id: Ifb5483c55b172d3553deb80dbe27f2204b86ecdb
diff --git a/include/media/mediametadataretriever.h b/include/media/mediametadataretriever.h
index 0df77c1..1acfac3 100644
--- a/include/media/mediametadataretriever.h
+++ b/include/media/mediametadataretriever.h
@@ -77,7 +77,7 @@
     const char* extractMetadata(int keyCode);
 
 private:
-    static const sp<IMediaPlayerService>& getService();
+    static const sp<IMediaPlayerService> getService();
 
     class DeathNotifier: public IBinder::DeathRecipient
     {