code: public void resume() {
          synchronized (finishCallback) {
              if (!paused) {
                  FileDownloadLog.w(this, "require resume this queue(remain %d), but it is"
                          + " still running", mTasks.size());
                  return;
              }
  
              paused = false;
              mTasks.addAll(pausedList);
              pausedList.clear();
  
              if (workingTask == null) {
                  sendNext();
              } else {
                  workingTask.addFinishListener(finishCallback);
                  workingTask.start();
              }
          }
      }
docs: Resume the queue if the queue is paused.
  
  @see #pause()