I'm no longer maintaining this version. Please check out the native OS X app https://github.com/stevenla/GooglePlayMusicRemote
Google Music Hotkeys
Alfred 2.0 workflows and Applescripts to control Google Play Music
By Steven La
I've set the default hotkeys to F7, F8, and F9 for previous, play/pause, and next track like on my Macbook. Use KeyRemap4MacBook to remap the media keys to the F-keys.
Requires the Alfred Powerpack!
Command Line (Applescript)
Comes with Google Chrome and Safari variants. Both have the same syntax, just different files.
./chrome.applescript ACTION or
toggleRepeat. A full list of actions is availible from this gist