https://android.googlesource.com/platform/external/vulkan-validation-layers.git/+log/bcb80d06bbdc09..f47c534fee2f26f

This CL re-enables Vulkan with the new build files.

In particular, this roll contains a fix for a vs2017 signed/unsigned
mismatch warning as error.

BUG=chromium:683729

Change-Id: Id38e10f97702cac5a51ee194c81972861f15db21
Reviewed-on: https://chromium-review.googlesource.com/457278
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>