Roll src/third_party/dawn 4b0b7a532ab9..540ababb6bee (1 commits)

https://dawn.googlesource.com/dawn.git/+log/4b0b7a532ab9..540ababb6bee

git log 4b0b7a532ab9..540ababb6bee --date=short --no-merges --format='%ad %ae %s'
2019-11-22 cwallez@chromium.org Introduce a "callback" type in dawn.json

Created with:
  gclient setdep -r src/third_party/dawn@540ababb6bee

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
TBR=cwallez@google.com

Bug: None
Change-Id: I1b409205070ee8a42f7e4b9d12918c06d2857120
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1930878Reviewed-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@{#718127}

DEPS

@@ -303,7 +303,7 @@ 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': '4b0b7a532ab94497576e41fc83cac6937d91a9cc',
+  'dawn_revision': '540ababb6bee89c96e4eb7beed14e1dbcc377148',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.