Roll src/third_party/dawn e25ee25e7743..949f1e45f1dc (3 commits)

https://dawn.googlesource.com/dawn.git/+log/e25ee25e7743..949f1e45f1dc

git log e25ee25e7743..949f1e45f1dc --date=short --first-parent --format='%ad %ae %s'
2020-05-19 natlee@microsoft.com Refactor MapRequestTracker to be its own class file.
2020-05-19 jiawei.shao@intel.com Disallow the copies within the same buffer
2020-05-18 hugo.amiard@laposte.net D3D12: Implement UseDxc toggle to use DXC for HLSL compilation

Created with:
  gclient setdep -r src/third_party/dawn@949f1e45f1dc

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/+/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: None
Tbr: cwallez@google.com
Change-Id: I0cab6148884cf11e81105bc7d999b9d2f7e006e7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2208462Reviewed-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@{#769995}

DEPS

@@ -301,7 +301,7 @@ 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': 'e25ee25e774366f8c178ee5a9cb29def31ce9611',
+  'dawn_revision': '949f1e45f1dc8c40b3ba2ba182fc7209ead09032',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.