src/vs/workbench/browser/parts/compositeBarActions.ts/ToggleCompositePinnedAction/constructor
class ToggleCompositePinnedAction:	constructor(
		private activity: IActivity | undefined,
		private compositeBar: ICompositeBar
	) {
		super('show.toggleCompositePinned', activity ? activity.name : localize('toggle', "Toggle View Pinned"));

		this.checked = !!this.activity && this.compositeBar.isPinned(this.activity.id);
	}