polkit-kde-agent-1 binary package in Ubuntu Xenial amd64

 PolicyKit is an application-level toolkit for defining and handling the policy
 that allows unprivileged processes to speak to privileged processes.
 .
 It is a framework for centralizing the decision making process with respect to
 granting access to privileged operations (like calling the HAL Mount() method)
 for unprivileged (desktop) applications.
 .
 PolicyKit-Kde provides a D-Bus session bus service that is used to
 bring up authentication dialogs used for obtaining privileges.

Source package