/usr/lib/unity-settings-daemon-1.0/gtk-modules/at-spi2-atk.desktop is in libatk-adaptor 2.18.1-2ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 | [GTK Module]
Name=AT-SPI2 ATK
Description=Accessibility ToolKit GTK+ Module
X-GTK-Module-Name=gail:atk-bridge
X-GTK-Module-Enabled-Schema=org.gnome.desktop.interface
X-GTK-Module-Enabled-Key=toolkit-accessibility
|