/usr/include/ is in libgtkimageview-dev 1.6.4+dfsg-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/gtkimageview/
/usr/include/gtkimageview/gtkimageview.h
/usr/include/gtkimageview/gdkpixbufdrawcache.h
/usr/include/gtkimageview/gtkimagetooldragger.h
/usr/include/gtkimageview/gtkzooms.h
/usr/include/gtkimageview/gtkimagetoolpainter.h
/usr/include/gtkimageview/utils.h
/usr/include/gtkimageview/gtkiimagetool.h
/usr/include/gtkimageview/gtkimagescrollwin.h
/usr/include/gtkimageview/mouse_handler.h
/usr/include/gtkimageview/gtkimagetoolselector.h
/usr/include/gtkimageview/gtkanimview.h
/usr/include/gtkimageview/cursors.h
/usr/include/gtkimageview/gtkimageview-typebuiltins.h
/usr/include/gtkimageview/gtkimagenav.h