Bugzilla

You  could avoid that call/wait by using what you should already have.

let {addonData} = extension;
let appProvided = addonData.builtIn || addonData.signedState === AddonManager.SIGNEDSTATE_SYSTEM;

It is a little different...addon.isSystem tells you the addon is installed into a system location, whereas the above tells you it is a signed system addon.  For all practical purposes, I don't think it matters.  Worst case scenario is a user installs one of our system-signed addons, that's a pretty big edge case.

You  could avoid that call/wait by using what you should already have.

let {addonData} = extension;
let appProvided = addonData.builtIn || addonData.signedState === AddonManager.SIGNEDSTATE_SYSTEM;

It is a little different...addon.isSystem tells you the addon is installed into a system location, whereas the above tells you it is a signed system addon.  For all practical purposes, I don't think it matters.  Worst case scenario is a user installs one of our system-signed addons, that's a pretty big edge case.

see https://searchfox.org/mozilla-central/rev/3d39d3b7dd1b2be30692d4541ea681614e34c786/toolkit/components/extensions/Extension.jsm#2018-2019