Code review comment for lp:~phablet-team/mir/track-plug-state

+ if (is_plugged[mga::as_hwc_display(display_name)].load() == false)

Can be written

  if (!is_plugged[mga::as_hwc_display(display_name)])

~~~~

+ is_plugged[HWC_DISPLAY_PRIMARY].store(true);
+ is_plugged[HWC_DISPLAY_EXTERNAL].store(false);
+ is_plugged[HWC_DISPLAY_VIRTUAL].store(true);

Constructors should use initialization, not assignment