Roll src/third_party/skia ce240cc6fd8e..40d1246d0c80 (4 commits) (#12755)

https://skia.googlesource.com/skia.git/+log/ce240cc6fd8e..40d1246d0c80

git log ce240cc6fd8e..40d1246d0c80 --date=short --no-merges --format='%ad %ae %s'
2019-10-02 senorblanco@chromium.org Dawn: update to Skia getOpsRenderPass() API change.
2019-10-02 chinmaygarde@google.com Guard [MTLDevice maxBufferLength] behind an API availability check.
2019-10-02 jvanverth@google.com Revert "Add less granular version of GrFence for older Metal versions."
2019-10-02 recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com Roll recipe dependencies (trivial).

Created with:
  gclient setdep -r src/third_party/skia@40d1246d0c80

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/skia-flutter-autoroll
Please CC rmistry@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

Bug: None
TBR=rmistry@google.com

DEPS

@@ -26,7 +26,7 @@ vars = {
   'skia_git': 'https://skia.googlesource.com',
   # OCMock is for testing only so there is no google clone
   'ocmock_git': 'https://github.com/erikdoe/ocmock.git',
-  'skia_revision': 'ce240cc6fd8ec95bd051c7df2173dad2ae8f6ad6',
+  'skia_revision': '40d1246d0c8094e5926989e11802e1230e2922a9',
 
   # When updating the Dart revision, ensure that all entries that are
   # dependencies of Dart are also updated to match the entries in the

ci/licenses_golden/licenses_skia

-Signature: 28fc257accd9528c6d37e667c0f201f5
+Signature: 1ddade8c892c148927d9ba544df1dc59
 
 UNUSED LICENSES: