Roll src/third_party/skia/ cfbbcbe52..a83b903b6 (4 commits)

https://skia.googlesource.com/skia.git/+log/cfbbcbe52624..a83b903b601a

$ git log cfbbcbe52..a83b903b6 --date=short --no-merges --format='%ad %ae %s'
2017-09-21 angle-deps-roller Roll skia/third_party/externals/angle2/ d48261595..f32cd0b78 (1 commit)
2017-09-21 mtklein ok, add via_skp
2017-09-21 angle-deps-roller Roll skia/third_party/externals/angle2/ 1f9d68437..d48261595 (1 commit)
2017-09-21 herb Remove unsafe align4 call

Created with:
  roll-dep src/third_party/skia
BUG=763972


Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, see:
http://www.chromium.org/developers/tree-sheriffs/sheriff-details-chromium#TOC-Failures-due-to-DEPS-rolls


CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel
TBR=fmalita@chromium.org

Change-Id: I68df7307985eac3dd532e134701f0ef14ab3b63f
Reviewed-on: https://chromium-review.googlesource.com/677856
Reviewed-by: Skia Deps Roller <skia-deps-roller@chromium.org>
Commit-Queue: Skia Deps Roller <skia-deps-roller@chromium.org>
Cr-Commit-Position: refs/heads/master@{#503640}