Roll src/third_party/dawn 3c79cf2ab9f2..2c8b5c637028 (3 commits)

https://dawn.googlesource.com/dawn.git/+log/3c79cf2ab9f2..2c8b5c637028

git log 3c79cf2ab9f2..2c8b5c637028 --date=short --no-merges --format='%ad %ae %s'
2019-10-21 cwallez@chromium.org Introduce the webgpu[_cpp].h headers.
2019-10-21 rharrison@chromium.org Rolling 3 dependencies
2019-10-21 rafael.cintron@microsoft.com Plug D3D 11on12 memory leak

Created with:
  gclient setdep -r src/third_party/dawn@2c8b5c637028

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: Ib1e0c945cd3524dbf7ce3af477d123eee30cf6a8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1872922Reviewed-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@{#708010}

DEPS

@@ -306,7 +306,7 @@ 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': '3c79cf2ab9f26f69d172c1cf71d63b31d89d20d1',
+  'dawn_revision': '2c8b5c637028dd25e47de5fa1db079619d27b122',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.