Roll src/third_party/skia 6e86c1b05eeedc3b6be0e98001b7b5d6bab71b74..6980c4e0aef8ab9546e25d8160c05a716f1c3ce3 (4 commits) (flutter/engine#10275)

https://skia.googlesource.com/skia.git
/compare/6e86c1b05eee..6980c4e0aef8

git log 6e86c1b05eee..6980c4e0aef8 --date=short --no-merges --format=%ad %ae %s
2019-07-30 egdaniel@google.com Remove isConfigCopyable from GrCaps.
2019-07-30 fmalita@chromium.org [skottie] Safe div-by-zero in LevelsEffectAdapter::apply
2019-07-30 michaelludwig@google.com Remove use of SkDropShadowImageFilter::ShadowMode internally
2019-07-30 bungeman@google.com Fix potential use of uninitialized data in with GDI.

The AutoRoll server is located here: https://autoroll.skia.org/r/skia-flutter-autoroll

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff (benjaminwagner@google.com), and stop
the roller if necessary.

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': '6e86c1b05eeedc3b6be0e98001b7b5d6bab71b74',
+  'skia_revision': '6980c4e0aef8ab9546e25d8160c05a716f1c3ce3',
 
   # When updating the Dart revision, ensure that all entries that are
   # dependencies of Dart are also updated to match the entries in the

engine/src/flutter/ci/licenses_golden/licenses_skia

@@ -1,4 +1,4 @@
-Signature: 27fd969b403c0944b8cac885a5eadfb7
+Signature: ed94631abc149042d9f608907285253e
 
 UNUSED LICENSES: