Roll src/third_party/skia 6f1c20f01fa9..28a8f28b3eaf (2 commits) (#13348)

https://skia.googlesource.com/skia.git/+log/6f1c20f01fa9..28a8f28b3eaf

git log 6f1c20f01fa9..28a8f28b3eaf --date=short --no-merges --format='%ad %ae %s'
2019-10-25 bsalomon@google.com Rename functions in TestUtils.h
2019-10-24 recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com Roll recipe dependencies (trivial).

Created with:
  gclient setdep -r src/third_party/skia@28a8f28b3eaf

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 michaelludwig@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=michaelludwig@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': '6f1c20f01fa923cd0029aace7b39aef62ff3ed2a',
+  'skia_revision': '28a8f28b3eaf5fc9a1019ca402eebfbfc1a2f0ba',
 
   # 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: 999ce8b65a4378f9442aaaba31a0bb63
+Signature: 3fdca8460f51a20cff9fe157b5f4c18f
 
 UNUSED LICENSES: