Embassy websites are inaccurate and out of date, and don't deal with TWOV very well. Forget about that. If you wish to take a printout of TIMATIC, you can. I would expect China Eastern check-in staff at California airports are well-acquainted with TWOV and that you won't have any issues boarding. However, I can tell that you are unconvinced by anything we say, and will worry yourself sick about this. Therefore, just go get a Chinese visa and be done with it. Spend the cash for peace of mind. And you can also be confident then, that you will be allowed to leave PVG and go to your Shanghai hotel. If you are located in the San Francisco Consular District and don't wish to go to the Chinese Consulate yourself, then use agent www.freechinavisa.org who is reliable and has reasonable service fees.