Implements focus traversal for desktop platforms, including re-implementing the existing focus manager and focus tree.
This implements a Focus widget that can be put into a widget tree to allow input focus to be given to a particular part of a widget tree.
It incorporates with the existing FocusScope and FocusNode infrastructure, and has minimal breakage to the API, although FocusScope.reparentIfNeeded is removed, replaced by a call to FocusAttachment.reparent(), so this is a breaking change:
FocusScopeNodes must now be attached to the focus tree using FocusScopeNode.attach, which takes a context and an optional onKey callback, and returns a FocusAttachment that should be kept by the widget that hosts the FocusScopeNode. This is necessary because of the need to make sure that the focus tree reflects the widget hierarchy.
Callers that used to call FocusScope(context).reparentIfNeeded in their build method will call reparent on a FocusAttachment instead, which they will obtain by calling FocusScopeNode.attach in their initState method. Widgets that own FocusNodes will need to call dispose on the focus node in their dispose method.
Addresses #11344, #1608, #13264, and #1678Fixes#30084Fixes#26704
* Added support for authentication codes for the VM service.
Previously, a valid web socket connection would use the following URI:
`ws://127.0.0.1/ws`
Now, by default, the VM service requires a connection to be made with a
URI similar to the following:
`ws://127.0.0.1:8181/Ug_U0QVsqFs=/ws`
where `Ug_U0QVsqFs` is an authentication code generated and shared by
the
service.
This behavior can be disabled with the `--disable-service-auth-codes`
flag.
Previously, I used the Android emulator for testing and everything
seemed to work fine with stdout (if I remember correctly). But our
devicelab uses real Android devices and the warnings are routed to
stderr. Hence change stdout to stderr in the test.
## Description
Print actionable warnings if `flutter drive` (where most of our performance benchmarks come from) is run in debug mode and it tries to gather benchmarks using `traceAction`.
## Related Issues
https://github.com/flutter/flutter/issues/30625
## Tests
I added the following tests:
* drive_perf_debug_warning devicelab test
updates the regex the analyzer uses, so it should be able to recognize expressions such as
const Foo a = Foo(); as "other code" rather than a constructor call.
