/usr/share/dbus-1/services/com.canonical.Thumbnailer.service is in thumbnailer-service 2.4+16.04.20160321-0ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 | [D-BUS Service]
Name=com.canonical.Thumbnailer
Exec=/usr/lib/x86_64-linux-gnu/thumbnailer/thumbnailer-service
|