@Override
 protected void onDestroy() {
   if (mStorageManager != null && mStorageListener != null) {
     mStorageManager.unregisterListener(mStorageListener);
   }
   if (mCameraDevice != null) mCameraDevice.release();
   super.onDestroy();
 }
  @Override
  protected void onPause() {
    super.onPause();

    unregisterReceiver(mUsbStateReceiver);
    if (mStorageManager == null && mStorageListener != null) {
      mStorageManager.unregisterListener(mStorageListener);
    }
  }