Code review comment for lp://staging/~gerboland/qtmir/acquire-wakelock

To test, this command is handy:
sudo powerd-cli list
it lists the various wakelocks enabled:

Example output with system (grabbed by unity8 here) and display wakelock:
  Name: com.canonical.Unity.Screen, Owner: :1.16, State: 1
  Name: active, Owner: :1.48, State: 1

Example output with display wakelock alone:
  Name: com.canonical.Unity.Screen, Owner: :1.16, State: 1

Example output with display off, but system wakelock still held by unity8/qtmir - is held for 3 seconds after display is turned off, to give apps time to save state before suspend:
  Name: active, Owner: :1.48, State: 1

3 seconds after screen blank:
  None