Roll Dawn from ab4e4feb01ac to e8dc820fbc1e (2 revisions)

https://dawn.googlesource.com/dawn.git/+log/ab4e4feb01ac..e8dc820fbc1e

2020-08-21 enga@chromium.org Skip TextureSubresourceTest.MipmapLevelsTest on Vulkan w/ validation
2020-08-20 bryan.bernhart@intel.com D3D12: check if resource manager exists before releasing

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/dawn-chromium-autoroll
Please CC cwallez@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/master/autoroll/README.md

Cq-Include-Trybots: luci.chromium.try:dawn-linux-x64-deps-rel;luci.chromium.try:dawn-mac-x64-deps-rel;luci.chromium.try:dawn-win10-x64-deps-rel;luci.chromium.try:dawn-win10-x86-deps-rel
Bug: chromium:1117595
Tbr: cwallez@google.com
Change-Id: If855398d377cdb4361f4f5fcd62a7d10e7f20b64
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2368477Reviewed-by: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#800429}

DEPS

@@ -318,7 +318,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.
-  'dawn_revision': 'ab4e4feb01ac2e3fc4d202ebf261817b664b69d9',
+  'dawn_revision': 'e8dc820fbc1e28eba80b8e8c49bb3e566874f4e7',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.