@Override
 public void onDestroy() {
   super.onDestroy();
   if (mClearBrowsingDataDialogFragment != null) {
     // In case the progress dialog is still showing and waiting for a callback, dismiss it.
     // See bug http://b/13396757.
     mClearBrowsingDataDialogFragment.dismissProgressDialog();
   }
   mClearBrowsingDataDialogFragment = null;
 }
 private void showClearBrowsingDialog() {
   mClearBrowsingDataDialogFragment = new ClearBrowsingDataDialogFragment();
   mClearBrowsingDataDialogFragment.show(
       getFragmentManager(), ClearBrowsingDataDialogFragment.FRAGMENT_TAG);
 }