Roll external/skia 091c02f89b64..f7281db422b7 (3 commits)

https://skia.googlesource.com/skia.git/+log/091c02f89b64..f7281db422b7

2019-11-15 skia-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/externals/angle2 1b52f05868c9..5f4db6a76640 (9 commits)
2019-11-15 skia-autoroll@skia-public.iam.gserviceaccount.com Roll ../src 7ca6de3adb8e..6961018759e7 (8341 commits)
2019-11-15 skia-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/externals/swiftshader b2407dd746de..102fd19c65f4 (4 commits)

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 nifong@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: I8f0756d9ad8d27273581b266e49b889c531872ca
Exempt-From-Owner-Approval: The autoroll bot does not require owner approval.