It is unlikely Google was asking the NSA to help secure their data-centers, it is more likely that Google was sharing information on the attacks and asking if the NSA had any corroborating evidence about it's source in the People's Liberation Army.

When tech companies face a coordinated foreign attack like this, they are looking to share attack data with one another, as well as the government, in order to form a complete picture of the attacker.

Let's put it this way. I could let you sit at my desk, give you my password, even let you edit code and try to submit it, and you would not be able to do anything harmful except perhaps get some of my personal data off my own hard disk. I'd even let you install a keylogger and it wouldn't help. You might be able to see internal design docs of unreleased Google products, but you would not be able to invade user privacy. That ship has sailed.