Code review comment for lp:~gerboland/qtubuntu/surface-visible-hidden-side-channel

To test, fetch this file and save on the device:
http://people.canonical.com/~gerboland/dateTime.qml
Run it with this command (with shell unlocked):

QSG_RENDER_TIMING=1 qmlscene dateTime.qml
--desktop_file_hint=/usr/share/applications/address-book-app.desktop

You should see the time printed on screen, and being printed on your
console once per second. You'll also see rendering statistics once per frame.

Now hit your power key. You should see that the render statistics stop,
yet you still get the time printed on your console. (note lifecycle
doesn't apply to manually started apps).

Hit the power key again, and unlock the greeter. Rendering should resume
immediately.