Re-add access of DisplayClient from vr_rm

This was removed in a previous commit because it relied on an in-flight
CL that had not yet landed. Now that it has landed, the change is back
in.

Bug: 36139334
Test: Compile and run VR app, confirm that touch region is correct
      through hierarchy viewer.

Change-Id: I4ecc5e050fd896ba7442eac8b3a4e0b793915ed7