Try clicking around https://source.chromium.org/chromium/chromium/src, which is built with Kythe (I believe, or perhaps it's using something internal to Google that Kythe is the open source version of).
By hooking into C++ compilation, Kythe is giving you things like _macro-aware_ navigation. Instead of trying to process raw source text off to the side, it's using the same data the compiler used to compile the code in the first place. So things like cross-references are "perfect", with no false positives in the results: Kythe knows the difference between two symbols in two different source files with the same name, whereas a search engine naively indexing source text, or even something with limited semantic knowledge like tree sitter, cannot perfectly make the distinction.
Yes the clicking around on semantic links on source.chromoum.org is served off of an index built by the Kythe team at Google.
The internal Kythe has some interesting bits (mostly around scaling) that aren't open sourced, but it's probably doable to run something on chromium scale without too much of that.
The grep/search box up top is a different index, maintained by a different team.
By hooking into C++ compilation, Kythe is giving you things like _macro-aware_ navigation. Instead of trying to process raw source text off to the side, it's using the same data the compiler used to compile the code in the first place. So things like cross-references are "perfect", with no false positives in the results: Kythe knows the difference between two symbols in two different source files with the same name, whereas a search engine naively indexing source text, or even something with limited semantic knowledge like tree sitter, cannot perfectly make the distinction.