Roll Skia from 3193ff271628 to 2a4c0fbdca1a (3 revisions)

https://skia.googlesource.com/skia.git/+log/3193ff271628..2a4c0fbdca1a

2021-01-22 brianosman@google.com Improve memory layout handling in SPIRV generator
2021-01-22 adlai@google.com Merge adjacent GrOpsTasks with same target together
2021-01-22 johnstiles@google.com Consolidate SkSL CPU and GPU test code.

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 scroggo@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/+doc/master/autoroll/README.md

Author: skia-flutter-autoroll

DEPS

@@ -27,7 +27,7 @@ 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': '3193ff271628b62b0d1428c191fac0c9437ce458',
+  'skia_revision': '2a4c0fbdca1a360884661e51e2bda3e8dd5579cd',
 
   # 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

@@ -1,4 +1,4 @@
-Signature: 49c89eeb3c131b477633487b44a5ac04
+Signature: 11111a59c83f474af5b3f0723bb41032
 
 UNUSED LICENSES: