Migrate media output switcher metrics - 3/n

Bug: 172181610
Test: run statsd_testdrive 277 and check the
output correctness after content switching.

Change-Id: I5abb471452ec92670d220b2472eadbe77e243653

src/com/android/settings/media/MediaOutputSlice.java

@@ -399,7 +399,7 @@ public class MediaOutputSlice implements CustomSliceable {
 
     @Override
     public Class getBackgroundWorkerClass() {
-        return MediaOutputSliceWorker.class;
+        return MediaDeviceUpdateWorker.class;
     }
 
     private boolean isVisible() {