A GPUImageHistogramFilter doesn't operate like a normal filter, and you can't use its output directly. It sends out a 3x256 texture containing the RGB channel histogram, but you need some way of parsing that for display. You won't be able to set that up in a GPUImageFilterPipeline construct.
Instead, you'll want to set up your filter pipeline manually, following the example provided in the FilterShowcase sample application (or my steps in the answer you link above). I use a histogram generator to create the overlay you see in the example there, and there's no easy way to set that up with a GPUImageFilterPipeline.
Also, I'd personally recommend not using the GPUImageFilterPipeline, since I don't maintain that class. It was contributed by a couple of other people, but I don't use it for anything myself and it has a tendency to break. I'd instead just create your filter chain yourself or place things within a GPUImageFilterGroup if you need to organize filter subunits.