The article says the MSFT will be a significant contributor to Chromium. If anything, this means that Google will have _less_ control, as a second major internet player will be involved.
Who is the current Chromium project lead? What's the decision making process? How can MS employees participate? How can MS employees in the future go against the wishes of Google with regards to Chromium? Will we see revert wars?
There is no single project lead; there are OWNERS in various directories who make decisions collectively. I would be thrilled to see more non-Google OWNERS.
The decision-making process varies based on where in the codebase you are. Blink has a lot of details on this, because it's what impacts the web platform and where we've needed to work with the most external input; you can read the various process summaries on https://www.chromium.org/blink . Things are less well-specified as you move up the stack because there's been less need to specify them. Perhaps that will change going forward.
Employee participation is the same as for Opera, Intel, Samsung, Yandex, etc. today: review and commit code, be an OWNER, participate on the mailing lists. Chromium tries to be a true open-source project.
As for disagreements about direction, I think the existing web platform discussions among all vendors provide an example of how disparate companies can come together and try to agree directionally. People from Brave, Opera, etc. already participate in those forums despite basing their browsers on the Chromium core. Blink sets a high bar for shipping features that have interop risks, so it's already true that the goal is consensus rather than a fractured web. And I'm sure Microsoft would not be keen to use Chromium if they didn't feel like they would have significant directional input where desirable.
Most of the concerns expressed in these comments seem reasonable on their face but also sound like the people expressing them haven't actually contributed to Chromium/Blink. I encourage people to chip in changes and even express opinions on our mailing lists. We try to welcome such contributions :)
From my position sitting at the crossroads of Clang/LLVM and Chrome (the team I work on developed clang-cl), all the interactions I've seen with MSFT are positive.