The Flutter Driver example mod

This is a very simple mod intended to be used with flutter driver testing scripts.

It contains four buttons that all modify a counter.

Building

To add the example (with the Flutter Driver Extensions enabled for driving the mod), run the following:

$ fx set [x64|arm64] --available topaz/bundles/buildbot

This will include the package and its dependencies with the topaz build when you run

$ fx full-build

Testing

You can run these tests using the following command (so long as you've included //topaz/packages/examples/tests as one of the packages for your build):

$ fx run-test driver_example_mod_tests