I wouldn't be surprised if Google is keeping certain performance enhancements closed source so they can have a competive advantage over the competition that uses the Chromium source. They have been slowly making Android open source worse by not updating parts and moving things to closed source Google Play apps.
It looks like the code of conduct used to include a preface about don't be evil, that's what was removed.
“Preface
Don’t be evil.” Googlers generally apply those words to how we serve our users. But “Don’t be evil” is much more than that. Yes, it’s about providing our users unbiased access to information, focusing on their needs and giving them the best products and services that we can. But it’s also about doing the right thing more generally – following the law, acting honorably, and treating co-workers with courtesy and respect.
The Google Code of Conduct is one of the ways we put “Don’t be evil” into practice.”
“We’re open source but not open source enough to your liking” is a VERY strange criteria for “evil” when most other commercial software companies are not open source at all.