Do you mean the non-semantic indexing, which covered most of Google Code? Like grep-style supporting, but no real semantic data?

Or are you talking about the few repos that had semantic indexing via Kythe (chromium, android, etc)? We never got that working for generic random open repos, primarily because it requires so much integration with the build system. A series of three or four separate people on Kythe tried various experimentation for cheaply-enough hooking Kythe into arbitrary open repos, but we all failed.