MOUNTAIN VIEW, June 8 -- The way most people discover what Google is building next for Android has nothing to do with keynote stages or press releases. It happens in experimental software that almost nobody runs, parsed by a handful of developers willing to wade through unreleased code. Android Canary build 2606, which landed quietly in early June, contains two features that tell a specific story about where Google thinks the phone-as-expression-platform is heading.

One of them is about color. The other is about content creation. Neither is ready for general use. Both point at something Google has been circling for the better part of two years.

The color feature is the flashier of the two, at least visually. Android's Material You desig...