Roll external/skia db816992b..3cf781d0e (4 commits)
https://skia.googlesource.com/skia.git/+log/db816992b..3cf781d0e
2017-08-23 robertphillips@google.com Switch GrSmallPath renderer over to always using integer texture coordinates
2017-08-23 angle-deps-roller@chromium.org Roll skia/third_party/externals/angle2/ 96f6adfa8..e3d8628d1 (1 commit)
2017-08-23 mtklein@chromium.org add compile-time not-supported checks to runtime CPU checks
2017-08-23 brianosman@google.com Add an (optional) SkTaskGroup to GrContext
Test: Presubmit checks will test this change.
Change-Id: I73eb41dbf5ff611907244b57eb1a4054df8142ea