Roll src/third_party/skia a12f6cbff348..32803ff74448 (4 commits) (flutter#13312)

https://skia.googlesource.com/skia.git/+log/a12f6cbff348..32803ff74448

git log a12f6cbff348..32803ff74448 --date=short --no-merges --format='%ad %ae %s'
2019-10-23 robertphillips@google.com Add PrePreparedDesc to GrTextureOp
2019-10-23 robertphillips@google.com Revert "Rename gl_SampleMask to sk_SampleMask"
2019-10-23 robertphillips@google.com Revert "Rename sampleVariablesSupport() to sampleMaskSupport()"
2019-10-23 senorblanco@chromium.org Dawn: fix compile.

Created with:
  gclient setdep -r src/third_party/skia@32803ff74448

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

Author: skia-flutter-autoroll

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': 'a12f6cbff348f063237a12325e2b0f2008310613',
+  'skia_revision': '32803ff7444854c109d1a751a2f240812aca0d29',
 
   # 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: df2665950af5021b304104f0e2e10515
+Signature: 7a58a7e8b60f1b1e69ae079305b161c1
 
 UNUSED LICENSES: