code: public void pause() {
          synchronized (finishCallback) {
              if (paused) {
                  FileDownloadLog.w(this, "require pause this queue(remain %d), but "
                          + "it has already been paused", mTasks.size());
                  return;
              }
  
              paused = true;
              mTasks.drainTo(pausedList);
              if (workingTask != null) {
                  workingTask.removeFinishListener(finishCallback);
                  workingTask.pause();
              }
          }
  
      }
docs: Pause the queue.
  
  @see #resume()