Roll external/skia c3ff97a98b74..50299de39976 (1 commits)

https://skia.googlesource.com/skia.git/+log/c3ff97a98b74..50299de39976

2019-11-23 robertphillips@google.com Reland "Revert "Make FP optimizations helpers use SkAlphaType not GrColorType""

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://skia-autoroll.corp.goog/r/android-master-autoroll
Please CC djsollen@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

Test: Presubmit checks will test this change.
Change-Id: I1bde6a5be90ba276f35ddd6ea332da7110f2168a
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