/usr/include/mirserver/mir/shell/ is in libmirserver-dev 0.31.1-0ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/mirserver/mir/shell/abstract_shell.h
/usr/include/mirserver/mir/shell/display_configuration_controller.h
/usr/include/mirserver/mir/shell/display_layout.h
/usr/include/mirserver/mir/shell/focus_controller.h
/usr/include/mirserver/mir/shell/host_lifecycle_event_listener.h
/usr/include/mirserver/mir/shell/input_targeter.h
/usr/include/mirserver/mir/shell/persistent_surface_store.h
/usr/include/mirserver/mir/shell/shell.h
/usr/include/mirserver/mir/shell/shell_report.h
/usr/include/mirserver/mir/shell/shell_wrapper.h
/usr/include/mirserver/mir/shell/surface_ready_observer.h
/usr/include/mirserver/mir/shell/surface_specification.h
/usr/include/mirserver/mir/shell/surface_stack.h
/usr/include/mirserver/mir/shell/surface_stack_wrapper.h
/usr/include/mirserver/mir/shell/system_compositor_window_manager.h
/usr/include/mirserver/mir/shell/window_management_info.h
/usr/include/mirserver/mir/shell/window_manager.h
/usr/include/mirserver/mir/shell/window_manager_builder.h