This paragraph surprised me: > Furthermore it is the only reasonable way to keep a reference to a binary and a set of shared libraries that can be exec‘ed. In the model used on Windows and Mac, renderers are exec’ed as needed from the chrome binary. However, if the chrome binary, or any of its shared libraries are updated while Chrome is running, we‘ll end up exec’ing the wrong version. A version x browser might be talking to a version y renderer. Our IPC system does not support this (and does not want to!).

I think the Chrome team overthought this. If you update firefox and try to perform an action which spawns a new process, it just politely demands the user restart the browser.