Max ROI Pooling.

def max_roi_pooling(attrs, inputs, proto_obj):
    """Max ROI Pooling."""
    new_attrs = translation_utils._fix_attribute_names(attrs,
                                                       {'pooled_shape': 'pooled_size',
                                                        'spatial_scale': 'spatial_scale'
                                                       })
    return 'ROIPooling', new_attrs, inputs