/usr/include/mirclient/mir_toolkit/ is in libmirclient-dev 0.26.3+16.04.20170605-0ubuntu1.1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/mirclient/mir_toolkit/client_types.h
/usr/include/mirclient/mir_toolkit/cursors.h
/usr/include/mirclient/mir_toolkit/event.h
/usr/include/mirclient/mir_toolkit/events/
/usr/include/mirclient/mir_toolkit/events/event.h
/usr/include/mirclient/mir_toolkit/events/input/
/usr/include/mirclient/mir_toolkit/events/input/input_event.h
/usr/include/mirclient/mir_toolkit/events/input/keyboard_event.h
/usr/include/mirclient/mir_toolkit/events/input/pointer_event.h
/usr/include/mirclient/mir_toolkit/events/input/touch_event.h
/usr/include/mirclient/mir_toolkit/events/input_configuration_event.h
/usr/include/mirclient/mir_toolkit/events/input_device_state_event.h
/usr/include/mirclient/mir_toolkit/events/keymap_event.h
/usr/include/mirclient/mir_toolkit/events/orientation_event.h
/usr/include/mirclient/mir_toolkit/events/prompt_session_event.h
/usr/include/mirclient/mir_toolkit/events/resize_event.h
/usr/include/mirclient/mir_toolkit/events/surface_event.h
/usr/include/mirclient/mir_toolkit/events/surface_output_event.h
/usr/include/mirclient/mir_toolkit/events/surface_placement.h
/usr/include/mirclient/mir_toolkit/events/window_event.h
/usr/include/mirclient/mir_toolkit/events/window_output_event.h
/usr/include/mirclient/mir_toolkit/events/window_placement.h
/usr/include/mirclient/mir_toolkit/extensions/
/usr/include/mirclient/mir_toolkit/extensions/android_buffer.h
/usr/include/mirclient/mir_toolkit/extensions/android_egl.h
/usr/include/mirclient/mir_toolkit/extensions/fenced_buffers.h
/usr/include/mirclient/mir_toolkit/extensions/gbm_buffer.h
/usr/include/mirclient/mir_toolkit/extensions/graphics_module.h
/usr/include/mirclient/mir_toolkit/extensions/mesa_drm_auth.h
/usr/include/mirclient/mir_toolkit/extensions/set_gbm_device.h
/usr/include/mirclient/mir_toolkit/extensions/window_coordinate_translation.h
/usr/include/mirclient/mir_toolkit/mir_blob.h
/usr/include/mirclient/mir_toolkit/mir_buffer.h
/usr/include/mirclient/mir_toolkit/mir_buffer_stream.h
/usr/include/mirclient/mir_toolkit/mir_client_library.h
/usr/include/mirclient/mir_toolkit/mir_connection.h
/usr/include/mirclient/mir_toolkit/mir_cookie.h
/usr/include/mirclient/mir_toolkit/mir_cursor_configuration.h
/usr/include/mirclient/mir_toolkit/mir_display_configuration.h
/usr/include/mirclient/mir_toolkit/mir_error.h
/usr/include/mirclient/mir_toolkit/mir_extension_core.h
/usr/include/mirclient/mir_toolkit/mir_input_device.h
/usr/include/mirclient/mir_toolkit/mir_persistent_id.h
/usr/include/mirclient/mir_toolkit/mir_platform_message.h
/usr/include/mirclient/mir_toolkit/mir_presentation_chain.h
/usr/include/mirclient/mir_toolkit/mir_prompt_session.h
/usr/include/mirclient/mir_toolkit/mir_screencast.h
/usr/include/mirclient/mir_toolkit/mir_surface.h
/usr/include/mirclient/mir_toolkit/mir_wait.h
/usr/include/mirclient/mir_toolkit/mir_window.h
/usr/include/mirclient/mir_toolkit/mir_window_id.h
/usr/include/mirclient/mir_toolkit/rs/
/usr/include/mirclient/mir_toolkit/rs/mir_render_surface.h
/usr/include/mirclient/mir_toolkit/version.h