/usr/include/ is in libmate-slab-dev 1.12.1-2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/libmate-slab/
/usr/include/libmate-slab/document-tile.h
/usr/include/libmate-slab/nld-marshal.c
/usr/include/libmate-slab/mate-utils.h
/usr/include/libmate-slab/nameplate-tile.h
/usr/include/libmate-slab/libslab-utils.h
/usr/include/libmate-slab/application-tile.h
/usr/include/libmate-slab/system-tile.h
/usr/include/libmate-slab/search-context-picker.h
/usr/include/libmate-slab/app-resizer.h
/usr/include/libmate-slab/search-entry.h
/usr/include/libmate-slab/slab-mate-util.h
/usr/include/libmate-slab/tile.h
/usr/include/libmate-slab/directory-tile.h
/usr/include/libmate-slab/search-entry-watermark.h
/usr/include/libmate-slab/bookmark-agent.h
/usr/include/libmate-slab/double-click-detector.h
/usr/include/libmate-slab/slab.h
/usr/include/libmate-slab/search-bar.h
/usr/include/libmate-slab/shell-window.h
/usr/include/libmate-slab/nld-marshal.h
/usr/include/libmate-slab/slab-section.h
/usr/include/libmate-slab/app-shell.h