This is a reland of 96c4019214e0b2d7c0843eacf96398a6a1198d1f
It includes a fix to add a dummy descriptor count if the
VkDescriptorPool would be empty, and adds a test that a bind group
with an empty bind group layout may be created and used.
Original change's description:
> Slab-allocate VkDescriptorSets
>
> This introduces a slab allocator for VkDescriptorSets which creates
> a VkDescriptorPool pre-allocated with multiple VkDescriptorSets per
> BindGroupLayout. In the future, we can deduplicate pools that have
> the same, or roughly the same, descriptor counts.
>
> This CL also removes the old DescriptorSetService and moves most of
> the functionality onto the DescriptorSetAllocator itself to keep
> the tracking logic in one place.
>
> Bug: dawn:340
> Change-Id: I785b17f4353fb3d40c9ccc33746600d6794efe7c
> Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/19320
> Reviewed-by: Austin Eng <enga@chromium.org>
> Commit-Queue: Austin Eng <enga@chromium.org>
Bug: dawn:340
Change-Id: Iabb744f110d0cab442bb857b31c87ba46bf0ad7a
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/20321
Commit-Queue: Austin Eng <enga@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>