Well the source for Chrome is not open (edit: correction acknowledged - I thought only Chromium was open), though if you are a Chrome developer confidently saying this is impossible then I would give merit to that. My experiences were non-scientific but still gave me enough suspicious to right this. I may try a more rigorous/careful/documented experiment sometime in the future.
The source to Chrome is definitely open and you can compile an effectively identical version yourself (minus the branding). There are some closed source plugins (eg. PDF and Flash) that are shipped as dynamic libraries. However, you could disable them (via about:plugins) or simply delete the corresponding binaries from a Chrome distribution and everything remaining would be open source.
When you say "effectively identical" do you mean all the preference defaults, all the Google service connection points, etc? Could I do a build from the Chrome source and get a hash match with the release build from Google?
