@Override
  protected @Nullable CloseableReference<CloseableImage> getCachedImage() {
    if (FrescoSystrace.isTracing()) {
      FrescoSystrace.beginSection("PipelineDraweeController#getCachedImage");
    }
    try {
      if (mMemoryCache == null || mCacheKey == null) {
        return null;
      }
      // We get the CacheKey
      CloseableReference<CloseableImage> closeableImage = mMemoryCache.get(mCacheKey);
      if (closeableImage != null && !closeableImage.get().getQualityInfo().isOfFullQuality()) {
        closeableImage.close();
        return null;
      }
      return closeableImage;
    } finally {
      if (FrescoSystrace.isTracing()) {
        FrescoSystrace.endSection();
      }
    }
  }
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