Moving permissions to optional on chrome extension

Question

I learned about Chrome disabling an extension when new permissions are added the hard way.

When I add new features to my extension I need to add new sites in the permissions list. Now I know I should have used optional_permissions.

My questions are:

1. If I move the site's list from permissions to optional_permissions does the user need to approve those sites again? or just the ones that I add over time.

2. Could any of these changes cause the extension to be disabled?:

   a. I add sites in the matches section of an entry in content_scripts

   b. I add sites in the matches section of an entry in externally_connectable

3. Is there a way to define externally_connectable in optional_permissions?

Related links: chrome.permissions | Permission Warnings

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Update: When Chrome disabled my extension I had added in the manifest one site on content_scripts > matches and externally_connectable with a matches site. The latter shows a new line in the permissions warnings saying "Communicate with cooperating websites". I'm not sure which change caused the disabling, that's why I ask about externally_connectable too.

Answer 1

In order to test when extensions are disabled by Chrome I created a private extension in the Chrome Web Store.

I started with a simple definition for manifest.json and then I added fields and settings one by one. For each test, I:

1. uploaded a new version to the store
2. waited for Google to publish the extension (this took a lot of time!)
3. forced the extension update on a testers' account
4. writed down the results

After 13 tests, this is what I've found:

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Changes in manifest that DISABLE the extension

• Adding an entry at "content_scripts" > "matches" [Warning: "Read and change your data on example.com"]
• Adding "externally_connectable" > {"ids", "matches"} [Warning: "Communicate with cooperating websites"]

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Changes in manifest that did NOT disabled the extension (no warnings)

• Adding "declarativeContent" permission
• Adding "optional_permissions" > all hosts
• Adding an entry at "externally_connectable" > "ids" (after externally_connectable was accepted)
• Adding an entry at "externally_connectable" > "matches" (after externally_connectable was accepted)
• Adding an entry of a host without permissions at "externally_connectable" > "matches" (after externally_connectable was accepted)
• Adding "incognito": "split"
• Adding "content_security_policy" > script-src URL
• Adding "web_accessible_resources"

Plus, permissions listed at permission_warnings#nowarning docs.

I probably did some silly tests like "web_accessible_resources", but I prefer that than having Chrome disabling my extension again.

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Special test

Since I'm moving to optional_permissions, all hosts listed in permissions are removed. So, I wanted to know what would happen with the disabled extension when a new update does not have the problematic permission anymore:

Update 1: a new host is added at "content_scripts" > "matches" => Extension disabled

Update 2: the problematic host is removed from "content_scripts" => Extension ENABLED again

To conclude, if you made a mistake you can release a new version rolling back the changes that caused the extension to be disabled.

If I move the site's list from permissions to optional_permissions does the user need to approve those sites again? or just the ones that I add over time.

The answer is straightforward, no. Chrome stores all permissions given to the extension over time. So, only the new hosts on optional_permissions need to be approved.