To reproduce:
1) Open https://cs.chromium.org/chromium/src/chrome/browser/ntp_snippets/download_suggestions_provider.cc

2) Click History

Expected:
It shows me partial results and does not show "Working..." for a very long time (i.e like git revision log does);

Actual:
It takes a very long time, I can wait, wait and wait, gave up, open https://chromium.googlesource.com/chromium/src/+log/4fc5997a7496bc2b803d049ab0218c385f6d6427/chrome/browser/ntp_snippets/download_suggestions_provider.cc and see what I need in a partial results list.

(also there seems to be some caching, so this may be not reproducible)