This summer, Google revised its privacy policy to state that people's browsing activity "may be" combined with data from Gmail and other functions. The revised policy applies to new account holders by default, but only applies to existing users if they opt in. ProPublica looks at the implication of the move, writing that it could enable Google to "build a complete portrait of a user by name, based on everything they write in email, every website they visit and the searches they conduct."