No, they won't. Unless they have specific reasons (such as a tip-off) that you are trying to smuggle illegal materials (porn, propaganda etc for distribution in China), they will not care about this. They primary focus is on security relevant issues and items you need to pay duty on.

I never in my life had anyone check documents, laptop, cellphone or laptop contents in a routine check - anywhere in the world.

Of course, if you make trouble at the border and they take you in, they might check everything they can.

No, they won't. Unless they have specific reasons (such as a tip-off) that you are trying to smuggle illegal materials (porn, propaganda etc for distribution in China), they will not care about this. They primarily focus is on security-relevant issues and items for which you need to pay duty.

I never in my life had anyone check documents, laptop, cellphone or laptop contents in a routine check, anywhere in the world.

Of course, if you make trouble at the border and they take you in, they might check everything they can.