One day last year, John Evans (not his real name) received a message from his manager at Facebook telling him he was in line for a promotion. When they met the following day, she led him down a hallway praising his performance. However, when she opened the door to a meeting room, he came face to face with members of Facebook’s secretive “rat-catching” team, led by the company’s head of investigations, Sonya Ahuja.
The interrogation was a technicality; they already knew he was guilty of leaking some innocuous information to the press. They had records of a screenshot he’d taken, links he had clicked or hovered over, and they strongly indicated they had accessed chats between him and the journalist, dating back to before he joined the company.

Source: ‘They’ll squash you like a bug’: how Silicon Valley keeps a lid on leakers | Technology | The Guardian
You can always read this blog directly at https://social.coldstreams.com in the event these posts are censored on Facebook.
The article notes the internal secrecy is not just about product features but extends to workplace issues, potentially enabling a misogynist culture to develop at Google. Employees want to tell the world but will be fired if they leak anything about internal harassment.
Both companies are said to log print outs, and even put USB-dongle traps laying about containing data to see who might leak it. The companies hire private security firms to listen in on conversations in coffee shops, bars and restaurants to see if anyone might be leaking. (I once overhead a key strategy meeting of a competitor while sitting at a restaurant table with my wife. I took notes and turned everything over to my company’s executives.)
The two corporations that intensely spy on their own workers simultaneously claim they are not doing anything evil with our personal data – yet as recent reports indicate, they are indeed engaged in selling our personal life stories to the highest bidder.