I wanted explicit language from Chrome's docs about how it scopes storage.

Firefox provided it: "The simple storage module exports an object called storage that is persistent and scoped to your add-on." https://developer.mozilla.org/en-US/Add-ons/SDK/High-Level_A...

But all Chrome's docs said were the previously mentioned warning about not using it to store confidential user info.

So, to answer your question: caution

Actually, if you go back to my init commit on Github - you can see that I originally used the chrome.storage API. I extricated it from the code - except for the non-sensitive settings