Unless things have changed from a couple of years ago (highly doubt it), I don't think this is the case. https://groups.google.com/a/chromium.org/d/msg/chromium-exte...
Why couldn't you use chrome.storage.local or the background page's localStorage? Either should protect the data from other extensions and not expose it to third parties.
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