Add remote media slice in volume panel

-Add test cases

Bug: 142772656
Test: make -j42 RunSettingsRoboTests
Change-Id: I62d3054a4343ed2c7fbb0b4d7aeb5a48da194b02

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

@@ -146,6 +146,17 @@ public class MediaDeviceUpdateWorker extends SliceBackgroundWorker
         return mTopDevice;
     }
 
+    /**
+     * Find the active MediaDevice.
+     *
+     * @param type the media device type.
+     * @return MediaDevice list
+     *
+     */
+    public List<MediaDevice> getActiveMediaDevice(@MediaDevice.MediaDeviceType int type) {
+        return mLocalMediaManager.getActiveMediaDevice(type);
+    }
+
     /**
      * Request to set volume.
      *