Nullify bineder/checkListener on destroy.

MyTracks/src/com/google/android/apps/mytracks/services/TrackRecordingService.java

@@ -130,7 +130,7 @@ public class TrackRecordingService extends Service implements LocationListener {
    * Task invoked by a timer periodically to make sure the location listener is
    * still registered.
    */
-  private final TimerTask checkLocationListener = new TimerTask() {
+  private TimerTask checkLocationListener = new TimerTask() {
     @Override
     public void run() {
       // It's always safe to assume that if isRecording() is true, it implies
@@ -710,7 +710,9 @@ public class TrackRecordingService extends Service implements LocationListener {
     showNotification();
     prefManager.shutdown();
     prefManager = null;
+    binder = null;
     checkLocationListener.cancel();
+    checkLocationListener = null;
     timer.cancel();
     timer.purge();
     unregisterLocationListener();
@@ -898,7 +900,7 @@ public class TrackRecordingService extends Service implements LocationListener {
   /**
    * The ITrackRecordingService is defined through IDL.
    */
-  private final ITrackRecordingService.Stub binder =
+  private ITrackRecordingService.Stub binder =
       new ITrackRecordingService.Stub() {
         @Override
         public boolean isRecording() {