What replaced ActionToolButtonView?

We have a custom legend tool implemented with Bokeh 2.4.3 (see below). I’m trying to migrate to Bokeg 3.4.1 but ActionToolButtonView seems to have gone and I’m not sure what has replaced it. How can I modify this code so it works with Bokeh 3? This issue is preventing me from upgrading.

import { ActionTool, ActionToolView, ActionToolButtonView } from "models/tools/actions/action_tool"
import { Legend } from "models/annotations/legend"


// View for toolbar icon for this tool
export class LegendToolButtonView extends ActionToolButtonView {
    _clicked() {
        if (this._menu) {
            this._menu.show();
        }
    }
}
LegendToolButtonView.__name__ = "LegendToolButtonView";

Probably ActionToolView, c.f.

bokeh/bokehjs/src/lib/models/tools/actions/action_tool.ts at branch-3.5 · bokeh/bokeh · GitHub