"Play null on" displayed under media volume

-Reset package name when it is different with previous one
-Add test case

Bug: 156224161
Test: make -j50 RunSettingsRoboTests
Change-Id: Ifcacc171d86017b702f51343036e0ebf0e0d1989

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

@@ -81,14 +81,17 @@ public class MediaOutputIndicatorWorker extends SliceBackgroundWorker implements
         mContext.registerReceiver(mReceiver, intentFilter);
         mLocalBluetoothManager.getEventManager().registerCallback(this);
 
-        if (mLocalMediaManager == null) {
-            final MediaController controller = getActiveLocalMediaController();
-            if (controller != null) {
-                mPackageName = controller.getPackageName();
-            }
-            mLocalMediaManager = new LocalMediaManager(mContext, mPackageName, null);
+        final MediaController controller = getActiveLocalMediaController();
+        if (controller == null) {
+            mPackageName = null;
+        } else {
+            mPackageName = controller.getPackageName();
+        }
+        if (mLocalMediaManager == null || !TextUtils.equals(mPackageName,
+                mLocalMediaManager.getPackageName())) {
+            mLocalMediaManager = new LocalMediaManager(mContext, mPackageName,
+                    null /* notification */);
         }
-
         mLocalMediaManager.registerCallback(this);
         mLocalMediaManager.startScan();
     }