Go-flutter: Flutter (Channel beta), v1.2.1 is released!

[pchampio]

The Changelog contains 2 Embedder API changes:

#7497 Embedder API: main_path and packages_path in FlutterProjectArgs have been renamed to indicate that they should no longer be provided.
#7567 Embedder API: The FlutterResult type has been renamed to FlutterEngineResult.

[pchampio]

Good news, none of the above changes breaks go-flutter.

[pchampio]

The following message appear when the go-flutter embedder is started:

[ERROR:flutter/shell/platform/embedder/embedder_surface_gl.cc(95)] Could not create a resource context for async texture uploads. Expect degraded performance. Set a valid make_resource_current callback on FlutterOpenGLRendererConfig.
[ERROR:flutter/shell/platform/embedder/embedder_surface_gl.cc(95)] Could not create a resource context for async texture uploads. Expect degraded performance. Set a valid make_resource_current callback on FlutterOpenGLRendererConfig.

The error is not critical.

[GeertJohan]

We should probably decide which channel we stick to. I'm usually using the dev channel, which was already at 1.2.2, but that channel is not stable at all.. Perhaps it's good to stay compatible with beta?

[pchampio]

Tracking Beta is good enough.

[GeertJohan]

As part of solving this issue, the flutter_embedder.h file should be updated to the upstream version linked to v1.2.1.

[GeertJohan]

I've already pushed version compatibility information directly to master, PR #81 to update embedder definitions.