In March, Fortune reported that Google had signed up Warner Music for an online music service similar but not identical to the popular Spotify service. Today, Greg Sandoval at The Verge is reporting that Universal and Sony Music have also signed on and the service will be launched tomorrow at Google I/O:

When Google rolls out the new services tomorrow at I/O, it will mean that it gets the jump on Apple, which is also trying to launch a new streaming-music service. According to reports, Google’s subscription services would resemble Spotify, and offer on-demand songs that would be streamed to their PCs and mobile devices. In contrast, Apple is working on an online radio service that is said to be more akin to Pandora, the top webcaster.

Google comes to these negotiations as a powerful player in music. While Google Play is still a relatively new service, insiders say YouTube is a juggernaut. The user-generated video site sees more than 800 million unique visitors a month and music videos are among the most popular fare.

I may not have exotic taste in music but I’ve never not been able to find whatever I want to listen to on YouTube. Google already owns the space and an advertising-based version of YouTube streaming is just a GUI change in my book.