I don't use spotify, but I do use apps from what I'm guessing are 3 different categories that handle media keys in different ways:
- apple apps (itunes, quicktime, etc)
- everything else (mplayerx, vlc, etc)
I bet spotify, rdio etc would get into one of those categories.
if chrome global keys are activated with the media keys (by any extension or google music app), everything works as expected, except for apple apps.
if I disable (or uninstall) chrome global keys, then the rest gets back to the normal expected behavior from the title, including opening itunes.
from all this I deduce there should be a way to get media keys to simply play the last thing that was played. always.
perhaps this question would be better for stackoverflow since, in practice, I'm already working to resolve this by abandoning itunes and quicktime. :P