The Labs feature only works in Chrome and it uses Native Client to bring many of the features of the Music Manager app to the browser (great news for Chrome OS users).
You first need to install the Play Music app from the Chrome Web Store.
You can enable a mini player that lets you control your music. The mini player doesn't work if you close the Play Music tab, so you still have to keep it open.
You can also upload your music directly from Chrome. Pick your folders or use the iTunes library. By default, Google will continue to monitor your folders and upload new music.
This is the "media file permissions" dialog:
I've picked my Music folder.
You can continue to use Play Music while the files are uploaded. Check the progress at the bottom of the window, in the left sidebar. Files are uploaded even if you close the Play Music tab.
If you don't have a lot of files to upload, use drag and drop. Just drag the files to the Play Music tab.
When downloading multiple files, Google used to create a ZIP archive. Now you can set a download folder and all the files are automatically downloaded to that folder.
"We built this lab using Chrome Apps and Native Client technology. Uploads, downloads and the mini player are just the start, and we are excited to push the boundaries of what's possible on the web," says Google.
{ via Google Play }
