service_constants: Add constant for IsShillSandboxingEnabled dbus method.

This constant denotes a dbus method that will be used to query whether
shill should run in a minijail.

BUG=chromium:649417
TEST=Check that go/crosr/1173260 compiles

Change-Id: If1cea8fc87df93071f1523c4fef54cbec82469bb
Reviewed-on: https://chromium-review.googlesource.com/1172729
Commit-Ready: Micah Morton <mortonm@chromium.org>
Tested-by: Micah Morton <mortonm@chromium.org>
Reviewed-by: Mattias Nissler <mnissler@chromium.org>
1 file changed