This kind of things happened in my case, and I was more happy to see the interest of the potential users than knowing who disclosed it as it would not be me anyway in all cases.
It might not be true in a small company/team/product. But in a big tech corps, the guy that will do the official announcement is usually quite far and unrelated to the engineers that did the feature.
Also, maybe a piece that was missing from my story is that the Googlers were not even in a team working or related to the disclosed thing. For example they were in the chrome team and it was an Android announcement or something like that.
Another point is that, at Google, it looks like that each big product team is firewalled from the other team. For example, people not working on Android core will not know anything about it or it's development and be in separated buildings and co.