They haven't worked on the base stuff of Android and ChromeOS. Both use Linux software abandoned by upstream, e.g. ChromeOS uses upstart and have their patched

They haven't worked on the base stuff of Android and ChromeOS. Both use Linux software abandoned by upstream, e.g. ChromeOS uses upstart and have their patched non-mainline kernels. This requires lots of extra work, then even doubled since they have 2 platforms. Wanting to have one mature platform for both makes sense to me.