@Override
  protected @Nullable Uri getMainUri() {
    return MultiUriHelper.getMainUri(
        mImageRequest,
        mLowResImageRequest,
        mFirstAvailableImageRequests,
        ImageRequest.REQUEST_TO_URI_FN);
  }
updateDebugOverlay updates the debug overlay. Subclasses of {@link PipelineDraweeController}
can override this method (and call <code>super</code>) to provide additional debug information.
drawee-backends/drawee-pipeline/src/main/java/com/facebook/drawee/backends/pipeline/PipelineDraweeController.java