In my experience in China only people in HK even know what weed is. I lived in main land china close to Deng Feng (shaolin temple) in Zeng Zhaou China and none of the rural main landers were even educated in what marijuana was and you could smoke it in front of military.... they didnt even know, many ppl in china roll up phat looking joints for thier tobacco so it looks normal to have a phat one rolled.
Hong Kong , Shanghai or beijing the people will definatley know all about pot and be smoking it.
Brownies im sure you would get away with but i guess it depends on circumstance, you could have somone who decides to chec the tubberware in your bag that goes thru the xray and if they crack it open and it smeels weed like you could be in shit.
Just eat a whole bunch before you head into security it will take a while to kick in anyways and you will be enjoying it in the air regardless.