Comparing Chinese tech companies with Google here feels like comparing apples and oranges and also "Chinese tech companies" is too big a entity to be compared with a single company.
But scenes at Yahoo/Reddit/Baidu and other smaller ads-driven companies aren't pretty
I recently posted a Ask HN asking about the effect of how drop in ads money would affect Google/FB and someone did a quick and dirty analysis for their runway: https://news.ycombinator.com/item?id=22884042
Just curious if Google has suffered similar level of revenue damage. If so it would be really bad since they got a hundred thousand people on paycheck.
I don't know the state of it, but Kythe is open source: https://kythe.io/
But in reality you probably want something more like SourceGraph which packages everything up nicely so that you don't need to worry about it, or something more specialized.
cs.opensource.google runs on Google's search infrastructure, so it's unlikely to be open sourced. https://github.com/google/zoekt is open source, but lacks cross-referencing, and has a more spartan UI.