Flickr/Yuri Samoilov
The changes were spotted in the Chromium issue tracker, which is Google's tool for keeping track of "bugs and feature development." The listing revealed a brief video of an app crashing on Android L; the video is only 20 seconds, but it shows off several new details about Android L, with regards to its design.
Here's the video:
As you can see along the top banner, the WiFi signal has changed, the clock is now bolder, and the Google Play icon has turned into what looks like a shopping bag. Along the bottom, the navigation icons are smaller but bolder, which allows them to be spaced further apart.
Android L was unveiled in June. The new update centers around a completely redesigned visual interface that's built to be more responsive, called "material design." You can learn more about Android L here.