/usr/include/opencv2/ is in libopencv-gpu-dev 2.4.8+dfsg1-2ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/opencv2/gpu/
/usr/include/opencv2/gpu/device/
/usr/include/opencv2/gpu/device/block.hpp
/usr/include/opencv2/gpu/device/border_interpolate.hpp
/usr/include/opencv2/gpu/device/color.hpp
/usr/include/opencv2/gpu/device/common.hpp
/usr/include/opencv2/gpu/device/datamov_utils.hpp
/usr/include/opencv2/gpu/device/detail/
/usr/include/opencv2/gpu/device/detail/color_detail.hpp
/usr/include/opencv2/gpu/device/detail/reduce.hpp
/usr/include/opencv2/gpu/device/detail/reduce_key_val.hpp
/usr/include/opencv2/gpu/device/detail/transform_detail.hpp
/usr/include/opencv2/gpu/device/detail/type_traits_detail.hpp
/usr/include/opencv2/gpu/device/detail/vec_distance_detail.hpp
/usr/include/opencv2/gpu/device/dynamic_smem.hpp
/usr/include/opencv2/gpu/device/emulation.hpp
/usr/include/opencv2/gpu/device/filters.hpp
/usr/include/opencv2/gpu/device/funcattrib.hpp
/usr/include/opencv2/gpu/device/functional.hpp
/usr/include/opencv2/gpu/device/limits.hpp
/usr/include/opencv2/gpu/device/reduce.hpp
/usr/include/opencv2/gpu/device/saturate_cast.hpp
/usr/include/opencv2/gpu/device/scan.hpp
/usr/include/opencv2/gpu/device/simd_functions.hpp
/usr/include/opencv2/gpu/device/static_check.hpp
/usr/include/opencv2/gpu/device/transform.hpp
/usr/include/opencv2/gpu/device/type_traits.hpp
/usr/include/opencv2/gpu/device/utility.hpp
/usr/include/opencv2/gpu/device/vec_distance.hpp
/usr/include/opencv2/gpu/device/vec_math.hpp
/usr/include/opencv2/gpu/device/vec_traits.hpp
/usr/include/opencv2/gpu/device/warp.hpp
/usr/include/opencv2/gpu/device/warp_reduce.hpp
/usr/include/opencv2/gpu/device/warp_shuffle.hpp
/usr/include/opencv2/gpu/devmem2d.hpp
/usr/include/opencv2/gpu/gpu.hpp
/usr/include/opencv2/gpu/gpumat.hpp
/usr/include/opencv2/gpu/stream_accessor.hpp