The AOSP common kernel has a couple of bugfixes that are not in the Chrome OS trees yet.  These should be evaluated, and backported to 3.14, 3.18, 4.4, and 4.9 if necessary:

https://android-review.googlesource.com/#/c/390812/
https://android-review.googlesource.com/#/c/269135/
https://android-review.googlesource.com/#/c/196296/

This is in our 4.4 tree but is not in all other trees:

https://chromium-review.googlesource.com/456669

There are a couple of others like this, too.  It would be useful to check all of the Chrome OS and Android branches to compile a list of the latest fixes, then make sure they are applied consistently across all four Chrome OS trees.

You can rerun the CTS traffic stats tests to verify that the kernel side is still working correctly.