src/vs/workbench/services/progress/browser/progressService.ts/ProgressService/withViewletProgress
class ProgressService:	private withViewletProgress<P extends Promise<R>, R = unknown>(viewletId: string, task: (progress: IProgress<IProgressStep>) => P, options: IProgressCompositeOptions): P {

		// show in viewlet
		const promise = this.withCompositeProgress(this.viewletService.getProgressIndicator(viewletId), task, options);

		// show on activity bar
		this.showOnActivityBar<P, R>(viewletId, options, promise);

		return promise;
	}