The issue tracker for the Android Open Source Project, more commonly known as AOSP, has always used Google Code. However, Code was completely shut down in 2016 (with most projects being forced to read-only in 2015), but the AOSP repository remained active.
Now the AOSP issue tracker has moved over to issuetracker.google.com, which first appeared publicly to collect bug reports from the Android O Developer Preview. All issues formerly at Google Code have been transitioned to the new Issue Tracker.
The new tracker is a major improvement over Google Code, and has been used by Google internally for a while now. This should help streamline development on Android moving forward, and make it easier for anyone to contribute.
- Android Developers Blog