Make MediaSessionManager#RESULT_MEDIA_KEY_*HANDLED as @SystemApi

Bug: 168143618
Test: m update-api -j;
Change-Id: I1529d5dc2a3a38a0b300f0297c3e689311244f40
diff --git a/non-updatable-api/module-lib-current.txt b/non-updatable-api/module-lib-current.txt
index f7f42d0..63b98cb 100644
--- a/non-updatable-api/module-lib-current.txt
+++ b/non-updatable-api/module-lib-current.txt
@@ -66,6 +66,8 @@
     method public boolean dispatchMediaKeyEventAsSystemService(@NonNull android.media.session.MediaSession.Token, @NonNull android.view.KeyEvent);
     method public void dispatchVolumeKeyEventAsSystemService(@NonNull android.view.KeyEvent, int);
     method public void dispatchVolumeKeyEventAsSystemService(@NonNull android.media.session.MediaSession.Token, @NonNull android.view.KeyEvent);
+    field public static final int RESULT_MEDIA_KEY_HANDLED = 1; // 0x1
+    field public static final int RESULT_MEDIA_KEY_NOT_HANDLED = 0; // 0x0
   }
 
 }