7d8c6d9c1 Reland add some AppLifecycleTests (#40455)

git@github.com:flutter/engine.git/compare/1b6344439062...7d8c6d9c1a5c

git log 1b6344439062..7d8c6d9c1a5c --no-merges --oneline
2019-09-13 xster@google.com Reland add some AppLifecycleTests


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 jimgraham@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

-1b63444390621ee2e81acddadf64babf7ec07e15
+7d8c6d9c1a5c1ce5303a5694bc9f49819c772f5f