We pipe the component name of the currently active dream into the
overlay service, and when the active dream is lowlight, we hide the
status bar.
Test: atest DreamOverlayStateControllerTest
Test: atest DreamOverlayStatusBarViewControllerTest
Test: manually on device by entering/exiting low light and ensuring the
status bar is hidden
Fixes: 245386662
Change-Id: I22973538bea19ef108360a319c70c878cfd81800