code: public void pauseAll() {
          FileDownloadTaskLauncher.getImpl().expireAll();
          final BaseDownloadTask.IRunningTask[] downloadList = FileDownloadList.getImpl().copy();
          for (BaseDownloadTask.IRunningTask task : downloadList) {
              task.getOrigin().pause();
          }
          // double check, for case: File Download progress alive but ui progress has died and relived
          // so FileDownloadList not always contain all running task exactly.
          if (FileDownloadServiceProxy.getImpl().isConnected()) {
              FileDownloadServiceProxy.getImpl().pauseAllTasks();
          } else {
              PauseAllMarker.createMarker();
          }
      }
docs: Pause all tasks running in FileDownloader.