In https://bugs.chromium.org/p/chromium/issues/detail?id=1243839 the styleguide was moved from https://chromium-cpp.appspot.com/ to https://chromium.googlesource.com/chromium/src/+/main/styleguide/c++/c++11.md.

There are references to the old url in https://github.com/openjdk/jdk/blob/master/doc/hotspot-style.html and https://github.com/openjdk/jdk/blob/master/doc/hotspot-style.md that should be updated.