We use a very similar system at Amazon. Our code review tool creates a diff and uploads it to a server. Once uploaded you publish the diff and wait for someone

We use a very similar system at Amazon. Our code review tool creates a diff and uploads it to a server. Once uploaded you publish the diff and wait for someone to approve it. Our team squashes and rebases before pushing to master but I know of other teams that leave the history as is. The only downside of the code review tool is that a large amount of changes is hard to grok. Breaking a single large code review into multiple small reviews generally counteracts that. It took some getting used to but it's powerful once you understand the development flow.