src/vs/workbench/contrib/extensions/browser/extensionsActions.ts/SetProductIconThemeAction/constructor
class SetProductIconThemeAction:	constructor(
		private productIconThemes: IWorkbenchProductIconTheme[],
		@IExtensionService extensionService: IExtensionService,
		@IWorkbenchThemeService private readonly workbenchThemeService: IWorkbenchThemeService,
		@IQuickInputService private readonly quickInputService: IQuickInputService
	) {
		super(`extensions.productIconTheme`, localize('product icon theme', "Set Product Icon Theme"), SetProductIconThemeAction.DisabledClass, false);
		this._register(Event.any<any>(extensionService.onDidChangeExtensions, workbenchThemeService.onDidProductIconThemeChange)(() => this.update(), this));
		this.enabled = true; // enabled by default
		this.class = SetProductIconThemeAction.EnabledClass;
		//		this.update();
	}