It looks like Google is working on a Google Play Music Chrome Packaged App

Chrome packaged apps

A rumor says that Google is working on a Chrome Packaged App of Google Play Music. That would be awesome, playing both local music files and cloud music files anywhere where Chrome is installed, in a specific app that acts like a native app. That is one more step into what I believe, that the Chrome Web Browser will become Chrome OS in the future.
Think about it: a music application that can run anywhere Chrome can; is able to play, edit and access local files, also stream back music from the cloud and offer music purchases with a built-in music store.
Source: Is A Google Play Music Packaged App In Development? | OMG! Chrome!