Android Developer Preview's are full of feature. Timely Introduce New feature like Multi window, Quick access Panel, Home screen shortcuts of Settings Menu Function, Quick reply and now Inbuilt VR Mode. Google Improving lots of Multi Usage Things support for Nexus Devices in upcoming android version.
How VR Mode It appears as though apps will be able to self-identify as VR Helpers and request access to the API that the user must agree to. Once granted, we assume VR Helper apps will provide headset popups whilst in VR Mode, which is also referenced in the Android N source code along with references to something called a VR Listener.