Roll external/skia 2563ff942..3727136ab (5 commits)
https://skia.googlesource.com/skia.git/+log/2563ff942..3727136ab
2017-10-13 bsalomon@google.com Implemenet onStealBackendTexture in GrMtlTexture
2017-10-13 reed@google.com remove dead code -- older than min picture version
2017-10-13 angle-deps-roller@chromium.org Roll skia/third_party/externals/angle2/ 3755c48d1..40dbdd6c7 (1 commit)
2017-10-13 halcanary@google.com platform_tools/android/bin/android_gdbserver: fix error
2017-10-13 bungeman@google.com Make SkTypeface::Style and FromOldStyle private.
Test: Presubmit checks will test this change.
Change-Id: I9ba8c8cc2cdf38588e63911d32e4783db116ba4a
Exempt-From-Owner-Approval: The autoroll bot does not require owner approval.