If an Activity transitions to VR, then ensure it's in the main stack.

Bug: 62791734
Test: Manual. From VR, start an app that sets VR dynamically via
Activity.setVrModeEnabled. Ensure it transitions from virtual display
to main display via added logging and 'adb shell am stack list'.

Change-Id: I11c1aad09e41666b928a6c2d896f9f2e22bb1aa5
1 file changed