arun@dell: ~/src/chromium/src $ du -sh third_party/ 4.8G third_party/
Out of the 95k commits, a mere 356 are from people outside of the google.com and chromium.org domains. Not sure how many of the chromium.org commits are from google employees.
PS: AUTHORS lists about 160 non-google employees, mostly sporting gmail.com email addresses.
I wish large open source projects that consume more open source code than they add, really stopped checking in everything they need into their own repo. Providing a chromiumos-overlay and a binhost would be a lot nicer to potential contributors. Most contributors I’m guessing have no interest in recompiling a gazillion third party dependencies.