@Override
      protected void onCancellationImpl() {
        try {
          if (FrescoSystrace.isTracing()) {
            FrescoSystrace.beginSection("MultiplexProducer#onCancellation");
          }
          Multiplexer.this.onCancelled(this);
        } finally {
          if (FrescoSystrace.isTracing()) {
            FrescoSystrace.endSection();
          }
        }
      }
Forwards {@link Consumer} methods to Multiplexer.
imagepipeline/src/main/java/com/facebook/imagepipeline/producers/MultiplexProducer.java