Do not apply maxAspectRatio to bounds when in VR mode.

VR applications use fullscreen always and should not have any aspect
ratio limitations applied. This CL addresses the issue by checking
the current mode before applying appBounds.

Change-Id: If8118833315af22917e5731cbc13bacb58a71a44
Fixes: 63024874
Test: launch VR activity, observe activity layout and nav bar placement
Test: go/wm-smoke