VulkanSwapChain: fix a problem in InitializeSwapChain() and add some DCHECK.

Bug: None
Change-Id: Ib855d479aa435d401de37496990eecc307a89eb5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1676678
Reviewed-by: Antoine Labour <piman@chromium.org>
Commit-Queue: Peng Huang <penghuang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672230}
1 file changed