I’ve heard “Mobile First!” a gadzillion times by now, but I’ve never took it too literally, and I don’t remember seeing anyone else who did. Google Operating System blog however suggest that Google does.
A few years ago, many people complained that mobile sites and mobile apps are too limited. They couldn’t include all the features from their desktop counterparts and some thought that was a bad thing.
Fast forward today and you’ll notice that Google’s desktop sites look more and more like Google’s mobile apps. Most Google redesigns are all about taking mobile interfaces and adding them to the desktop. That’s one of the reasons why many Google services drop advanced features and opt for simplified interfaces. This way, everything looks consistent and users can quickly switch from the mobile apps to the desktop apps.
There are also specific examples listed – Google Maps, Google Play, Google+ and others.