Google's ongoing lawsuit with Oracle!
Google does have a plan for bringing Android to PC's - but it's not quite what you are envisioning: Google wants to add the Android execution environment to Chrome. Android could -with a lot of work - by made to be installable on PC's, but bringing it to Chrome instead means it could be easily deployed to 25% of all computers immediately (25% being Chrome's ~ market share).
If you don't believe me, look at the smoking gun e-mail that Google is currently fighting to keep out of lawsuit - it refers to Google needing Java for Chrome.
I'm not suggesting that Google is going to suddenly drop Java if they lose the lawsuit - they are way too far committed to Java to do that - but they would like to at least know what the terms of using Java are going to be before they take a step that would significantly increase their dependence on it.