Roll engine 2d6631ae5d1c..728ff715e88f (4 commits) (#39437)

git@github.com:flutter/engine.git/compare/2d6631ae5d1c...728ff715e88f

git log 2d6631ae5d1c..728ff715e88f --no-merges --oneline
2019-08-28 iska.kaushik@gmail.com [fidl][flutter_runner] Port Migrate to new fit::optional compatible APIs (flutter/engine#11636)
2019-08-28 garyq@google.com Update the ui.LineMetrics.height metric to be more useful to external users (flutter/engine#11456)
2019-08-28 skia-flutter-autoroll@skia.org Roll src/third_party/skia b1ade2a4261e..a268dfb74add (5 commits) (flutter/engine#11643)
2019-08-28 brianosman@google.com Update CanvasSpy::onDrawEdgeAAQuad for Skia API change (flutter/engine#11638)


If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-engine-flutter-autoroll
Please CC garyq@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

bin/internal/engine.version

-2d6631ae5d1c480dc941bf9e79099fef7bc640d5
+728ff715e88f425b1d7589f0c857bd71e41c9195