Roll src/third_party/skia 0788481c63dc..7a538b1eeccd (3 commits) (#13973)

https://skia.googlesource.com/skia.git/+log/0788481c63dc..7a538b1eeccd

git log 0788481c63dc..7a538b1eeccd --date=short --no-merges --format='%ad %ae %s'
2019-11-22 bsalomon@google.com Make FP optimizations helpers use SkAlphaType not GrColorType
2019-11-22 reed@google.com Revert "Revert "Use flat version of path-direction enum""
2019-11-21 recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com Roll recipe dependencies (trivial).

Created with:
  gclient setdep -r src/third_party/skia@7a538b1eeccd

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 robertphillips@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=robertphillips@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': '0788481c63dc4c06fdeb0976cc5568ef85d06af0',
+  'skia_revision': '7a538b1eeccdbe940de507af9aeaf454952c4aec',
 
   # 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: c8ea729af1431890557e325f934d9a17
+Signature: 381c27cc50b515f1a409143c19c51f31
 
 UNUSED LICENSES: