pdb's exist for all builds of google chrome.

Interesting! No PE structures though, I suppose.

PE is only used for loading the dll, same works on linux.

I thought Linux uses ELF to load dlls.

ELF and PE are functionally the same, instead of DLL's you load SharedObject as your injeciton method, but you don't need that at all since you can inject libraries in linux since it's a built-in feature.