Persist `runtime.setUninstallURL()` until update

[carlosjeurissen]

Intro

Currently the persistence of runtime.setUninstallURL() differs per browser:

• Firefox does not persist the uninstallURL and requires it on every run of the background script
• Chrome/Edge persist the uninstallURL even after update

This leads to the following issues:

• Firefox does not open an uninstallURL when an extension is disabled beforehand (see Should disabled extensions have their runtime.setUninstallURL opened on uninstall? #970)
• Chrome/Edge in it's current shape can not undo setting an uninstallURL. If a developer wants to stop opening an uninstallURL, pushing an update without an uninstallURL will not impact existing installations where setUninstallURL() is called.

Orion seems to at least persist between browser sessions. However did not test if it is persisted on update.

Solution

All browsers persist the uninstallURL UNTIL and excluding in the case of an extension update, resolving both issues.

The only workaround right now in Chrome would be to use runtime.setUninstallURL('') indefinitely if historically it used an uninstallURL yet nolonger wants this in newer versions.

[Rob--W]

@oliverdunk will check on the acceptable behaviors in Chrome, and then we can consider aligning in Firefox. Likely considering to persist the uninstall URL, but not across extension updates.