resumeWhilePausing 属性表示:
Indicate that it is okay for this activity be resumed while the previous activity is in the process of pausing, without waiting for the previous pause to complete. Use this with caution: your activity can not acquire any exclusive resources (such as opening the camera or recording audio) when it launches, or it may conflict with the previous activity and fail.
大致意思是:表明在前一个Activity还在执行onPause()方法时(即在暂停过程中,还没有完全暂停),允许该Activity显示,但是要注意,这个Activity不能申请任何其他额外的资源,比如相机等。