When it comes to Android issue tracking, Google has always used Google Code. However, Google started phasing out Code for most users in 2013, and Google's projects are the only active repositories left. Now the company has started to shift to a new issue tracker, hosted at issuetracker.google.com.
The feedback page for Android O states that the new issue tracker has been used internally at Google for a while now, but now the site is publicly-accessible to help collect feedback and bug reports from Android O Dev Preview users. The tracker appears to be split into categories called 'components,' with Android O being one.