This is an automatic rename of various things related
to the window->surface rename.

Public symbols changed by this is:
 GDK_MODE_WINDOW
 gdk_device_get_window_at_position
 gdk_device_get_window_at_position_double
 gdk_device_get_last_event_window
 gdk_display_get_monitor_at_window
 gdk_drag_context_get_source_window
 gdk_drag_context_get_dest_window
 gdk_drag_context_get_drag_window
 gdk_draw_context_get_window
 gdk_drawing_context_get_window
 gdk_gl_context_get_window
 gdk_synthesize_window_state
 gdk_surface_get_window_type
 gdk_x11_display_set_window_scale
 gsk_renderer_new_for_window
 gsk_renderer_get_window
 gtk_text_view_buffer_to_window_coords
 gtk_tree_view_convert_widget_to_bin_window_coords
 gtk_tree_view_convert_tree_to_bin_window_coords

The commands that generated this are:

git sed -f g "GDK window" "GDK surface"
git sed -f g window_impl surface_impl
(cd gdk; git sed -f g impl_window impl_surface)
git sed -f g WINDOW_IMPL SURFACE_IMPL
git ...