Playtime is over in Android Land. Over the last couple of months Google has reached out to the major carriers and device makers backing its mobile operating system with a message: There will be no more willy-nilly tweaks to the software. No more partnerships formed outside of Google’s purview. From now on, companies hoping to receive early access to Google’s most up-to-date software will need approval of their plans. And they will seek that approval from Andy Rubin, the head of Google’s Android group.