@Override
  protected int getImageHash(@Nullable CloseableReference<CloseableImage> image) {
    return (image != null) ? image.getValueHash() : 0;
  }
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