"This is a big deal," McMaster says about mods.
The company is launching a set of new integrations, including Skype, Cortana, and Hyperlapse. There's a theme there: all of those services are made by Microsoft.
Microsoft was rumoured to have invested in Cyanogen, but instead it's working with the company to ship Cyanogen's version of Android complete with Microsoft services.
Cyanogen is now letting developers get more control over how a smartphone works using what it calls mods. They're more than an app - a mod makes functionality seem as if it's built into a smartphone's operating system.
You can view Instagram right on your lock screen, for example, or use Skype straight from the dialler app. Or you could ask Microsoft's virtual assistant Cortana to take a selfie of you and make it look pretty.
McMaster says this kind of enhanced integration is the future of computing, not things like virtual reality. "Everybody's so excited about VR. The phones put people to sleep now. The next step in computing is not VR, we think it's integrating these experiences into the mobile operating system because this gives rise to new kinds of experiences, new kinds of intelligences."
"You'll sell hundreds of millions of Android phones this year, and you'll sell, what, half a dozen Oculus devices?" he says. "By 2020 Android will be at around 4.6 billion users. iOS, plus Facebook daily active users on mobile, plus Windows PC will be about 4.4 to 4.5 billion users by 2020. In other words, Android will be bigger than all three of them combined. Android is a super platform and its potential is yet to even be realised."
McMaster's vision of the smartphone world is one where Android rules dominant, and app developers have much more control over what they can do. That's the polar opposite to Apple's walled garden approach.
He's also skeptical about the endless cycle of smartphone launches:
You're here at Mobile World Congress, what do you see? A whole bunch of goddamn rectangles. Big fucking deal. Who cares about rectangles? Nobody cares about rectangles anymore. It's all about applications and services, but you don't hear much interesting about applications and services.