That like 5 hours per night with 20 min to shower/get ready. Not great, but it can be done by taking meetings during your commute into work, having food delivered and eating/working at the same time. I assume that lady didn't have kids during her time at Google (when she was working those hours).
Edit: Marissa Mayer did not have kids during her time at Google. She had her first after she'd moved to Yahoo. There are no mentions of her hours there, so I assume they were less (not as fun to put into the article)