I noticed this comment in an old Alloy extension bug that was set to wontfix:
https://github.com/chromiumembedded/cef/issues/3114
changed state from "new" to "wontfix"
Extensions support will likely be removed from the Alloy runtime if/when it's no longer required to support the PDF viewer.
Will this happen in the Chrome framework too, or only for Alloy? We are still using Alloy with a custom extension but plan to switch to Chrome eventually.