🚫 **BLOCKED** : Do not merge until
https://github.com/flutter/flutter/issues/161261 (additional test
coverage).
---
This PR eliminates (1) `scenario_app/android`, and all references to an
Android `scenario_app`, including documentation, CI configuration, build
rules, test runner, Android-side test application, and (2), to verify
and disambiguate the remains, renames the folder `ios_scenario_app`,
which is now accurate.
It also eliminates elements that were _only_ used in the Android-side
scenario_app, such as Firebase Test Lab uploading.
I would be open to doing this in phases if we thought it was better to
do so, but given its mostly a mechanical change (and by renaming the
directory, references can be checked merely by looking for
`/\bscenario_app/`, I believe this is safe to iterate on and eventually
merge after the holidays.
## Background
As of the merged mono-repo, there is no longer a requirement for the
engine to be testable as a standalone unit.
As an example,
[`%ENGINE%/testing/scenario_app`](3762f2e973/engine/src/flutter/testing/scenario_app),
which was intended to _emulate_ the Flutter framework (and some of
`flutter_tools` tooling), load the iOS and Android embedder, and run
various "scenarios" (which ran a combination of `dart:ui` code and
Android Java/iOS Obj-C) verifying golden-file screenshots.
Instead, it is now possible to write and run _real_ (full) Flutter apps
the same way that an end-user (or our own tests) would. One such example
is
[`dev/native_driver_test`](https://github.com/flutter/flutter/tree/master/dev/integration_tests/native_driver_test),
which is a full-fledged Flutter app, which uses standard tooling (i.e.
`flutter`), to test most of the same elements that previously were only
tested in the Android version of `scenario_app`.
