I had to change

static const base::flat_map<std::string, MimeUtil::Codec> kStringToCodecMap({
  ...entries...
});

to

static const base::NoDestructor<base::flat_map<std::string, MimeUtil::Codec>> kStringToCodecMap(base::flat_map<std::string, MimeUtil::Codec>({
  ...entries...
}));

when making it NoDestructor.

Note the additional base::flat_map<std::string, MimeUtil::Codec>() ctor call.

Isn't perfect forwarding supposed to not require this? Or does that only work with uniform initialization?

Context:

https://chromium-review.googlesource.com/c/chromium/src/+/1246602/6/media/base/mime_util_internal.cc