Add null check for vrManager

If VrManagerService is not started, vrManager will be null. Need
add check for it.

Test: robotests
Bug: 116427118
Change-Id: I899337bb5a996efffe82970fa690f2c5d59c1bb5
Merged-In: I899337bb5a996efffe82970fa690f2c5d59c1bb5
2 files changed