Tom Williams via Getty Images Top executives from Meta, Twitter, YouTube and TikTok just wrapped up a three-hour hearing in front of the Senate Homeland Security Committee. The hearing, which featured Meta CPO Chris Cox, YouTube CPO Neal Mohan, TikTok COO Vanessa Pappas and Twitter’s GM of consumer product (known as “Bluebird”), was meant to be focused on how their services impact national security issues. Notably, the hearing is only the second time representatives for TikTok and YouTube had ever appeared at such a hearing — Meta and Twitter execs have been hauled in front of Congress far more often…