Roll Skia from 7cf3addb1bd8 to a4bd6ae59655 (2 revisions)

https://skia.googlesource.com/skia.git/+log/7cf3addb1bd8..a4bd6ae59655

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 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

Test: Presubmit checks will test this change.
Exempt-From-Owner-Approval: The autoroll bot does not require owner approval.
Change-Id: I61699b54c96f703a86be9162d81cd24651eccad1