Description

This adds support for game controller buttons. It adds some supplemental USB HID codes that aren't available from the Chromium source code, and maps those on Android to the game pad buttons that Android supports. Other platforms are not supported yet.

Related Issues

Addresses #31957

Paired with engine change that adds the source information for keyboard events: flutter/engine#9186

Tests

I added the following tests to check that:

• DPAD keys on joysticks give physical mappings even if the scanCode is zero.
• DPAD keys on keyboards give the right physical mappings still.
• DPAD_CENTER gives select as a logical key, and the correct physical key for the location of the DPAD used.

Checklist

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• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I signed the CLA.
• I read and followed the Flutter Style Guide, including Features we expect every widget to implement.
• I updated/added relevant documentation (doc comments with ///).
• All existing and new tests are passing.
• The analyzer (flutter analyze --flutter-repo) does not report any problems on my PR.
• I am willing to follow-up on review comments in a timely manner.
• I checked all the boxes.

Breaking Change

Does your PR require Flutter developers to manually update their apps to accommodate your change?

• No, this is not a breaking change.