Right, so here is seems how things are:
1. Google seems to have little regard for long term backwards compatibility, at least on the timeframes Debian wants it. Kernel 3.17 came out in October 2014. Fedora has a new enough kernel, but also doesn't have Chromium officially apparently because Google likes to clone various libraries and do API changes, rather than trying to work with the original developers, distributions, etc. So it seems Google mostly does its own thing and lets other people to deal with it.
2. So Google is now releasing browsers that require kernel 3.17 to work properly. Users want to run it on their systems.
3. But Jessie is frozen and so changes only happen for good reasons. The question is then whether to backport the TSYNC feature. On one hand, it's a new feature and it doesn't go in frozen releases, on the other hand it stops new versions of Chrome from running, which is a security concern. Ubuntu seems to have went with the later logic.
4. Ben's reaction is "1. I don't like Chrome, so no", and "2. Distro is in freeze, there needs to be a formal proposal explaining exactly what patch to merge, and a sympathetic maintainer, which I am not".
So really what's going on is a conflict between organizations. Google wants to move faster than Debian does, and Debian (or at least Ben) doesn't want to give Google special concessions.