Roll Skia from d4e19ac8c773 to 2c9a6ec3a0d0 (2 revisions)

https://skia.googlesource.com/skia.git/+log/d4e19ac8c773..2c9a6ec3a0d0

2021-06-07 ethannicholas@google.com Added skstd::string_view
2021-06-07 csmartdalton@google.com Fix tessellation GLSL issues on Mac

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/+doc/master/autoroll/README.md

Test: Presubmit checks will test this change.
Exempt-From-Owner-Approval: The autoroll bot does not require owner approval.
Bug: b/186777432
Change-Id: If8b40a01139ad7d912ae6a94687d543a7622526d