Add null check for vrManager

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

Test: build pass
Bug: 116427118
Change-Id: If834d0f061c99c61043696afc8f737be2f85459a
Merged-In: If834d0f061c99c61043696afc8f737be2f85459a
1 file changed