Roll external/skia d628747df..a4eecd804 (4 commits)

https://skia.googlesource.com/skia.git/+log/d628747df..a4eecd804

2019-06-25 herb@google.com findImage(const SkGlyph&) -> prepareImage(SkGlyph*)
2019-06-25 mtklein@google.com more aarch64 instructions
2019-06-25 jcgregorio@google.com Upgrade cipd package for vpython to latest.
2019-06-25 skia-autoroll@skia-public.iam.gserviceaccount.com Roll skia/third_party/skcms d7303797becf..4f682a1d0b94 (1 commits)

The AutoRoll server is located here: https://autoroll-internal.skia.org/r/android-master-autoroll

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

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.

Test: Presubmit checks will test this change.
Change-Id: I88b9a0a1ba205a4d831138013a9fbb5e364bd3e5
Exempt-From-Owner-Approval: The autoroll bot does not require owner approval.