Google I/O kicks off a busy developer season this week. Followed by Microsoft's developer conference later this week, then Facebook's F8 and finishing up with Apple's Worldwide Developers Conference in June. Leo says that both Google and Microsoft will have a message on Progressive Web Apps. These are apps that will be web centric, with the idea that you can download pieces of the app that will operate off line, but with the rest of the work on a backend in the cloud. Leo says that it's no longer about the operating system.