The credential manager is disabled while in VR because:
1. it displays popup dialogs in 2D on top of VR
2. privacy concerns (auto sign-in could work, but toasts that you were logged in automatically aren't shown while in VR, meaning users may do things thinking they weren't logged in).

We should re-enable this feature while in VR, but we need to make sure that dialogs, toasts, and infobars are shown correctly.  Some of these are hidden automatically by GVR because they are hosted in the normal view hierarchy rather than as a separate dialog.