[LayoutNG] Cleanup where we set the new exclusion space.

We don't need two separate logic paths to set the exclusion space.
We are able to update the exclusion space once we know we have a
successful child layout.

Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_layout_ng
Change-Id: I7aaa7ecfde69c4fedb71bbb77c2ccf4fc21aacf9
Bug: 635619
Reviewed-on: https://chromium-review.googlesource.com/1147331
Commit-Queue: Ian Kilpatrick <ikilpatrick@chromium.org>
Reviewed-by: Morten Stenshorne <mstensho@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579146}
1 file changed