1424904 - storage.sync should not require syncing add-ons

Status: RESOLVED FIXED

(WebExtensions :: Storage, defect)

Description

[Yuri Khan]

To reproduce:

0. Run “firefox --no-remote --ProfileManager” and create a new Firefox profile.
1. On the initial page, follow the link to create a new Firefox account.
2. When choosing what to synchronize, uncheck Add-ons.
3. From about:debugging, load temporary add-on, favourite-colour from github:mdn/webextensions-examples.
4. Click the browser action button of favourite-colour.
5. In the preferences page of favourite-colour, in the Favourite colour box, enter “fainted frog” and click Save.
6. On the sandwich menu, click the Sync (two circular arrows) button and wait until it stops animating.

7. Run “firefox --no-remote --ProfileManager” and create another new Firefox profile.
8. Log into the account created in step 1.
9. Wait for the Sync button on the sandwich menu to stop animating.
10. From about:debugging, load temporary add-on, favourite-colour from github:mdn/webextensions-examples.
11. Click the browser action button of favourite-colour.

Observed result: the Favourite colour box contains the default value of “Firefox red”.

12. In the profile created in step 0, open Preferences. On the Firefox Account tab, in the Sync Settings group, enable [x] Add-ons.
13. On the sandwich menu, click the Sync button and wait until it stops animating.
14. In the profile created in step 7, open Preferences. On the Firefox Account tab, in the Sync Settings group, enable [x] Add-ons.
15. On the sandwich menu, click the Sync button and wait until it stops animating.
16. Reload the favourite-colour preferences page.

Observed result: the Favourite colour box now contains “fainted frog”.

Expected behavior: It should be possible to sync extension storage without also syncing add-ons. As an example, the user might have extensions A and B on their home machine, and extensions B and C on their work machine where extension A is not approved for installation or otherwise undesirable. The storage of B should be synchronized. If the user subsequently installs extension C at home, it should see its storage data from the work machine.

Comment 1

[Andy McKay]

Thanks for the detailed bug. This was discussed in bug 1290440 and it was decided in that this felt like an edge case that would make our UX more complicated.

I haven't heard a big request for this, in fact you are the first. So I'm tempted to agree with the UX recommendations in that bug.

Comment 2

[Yuri Khan]

Well, look at it from my point.

First, the Sync section in the Preferences panel has a checkbox named [x] Preferences. It is pretty easy to infer storage.sync is controlled by that.

Second, the MDN documentation on storage.sync says:

> Items in sync storage are synced by the browser, and are available across all instances of that browser that the user is logged into (e.g. via Firefox sync, or a Google account), across different devices.

It then goes on to mention that the add-on must have an explicit ID, which is reasonable, and that there are total size limitations and lack of guarantee, which is understandable.

It does not mention that the user needs to enable add-on sync. So I expected storage.sync to sync automatically and unconditionally.

I would call it a documentation bug at least.

Also, bug 1290440 speaks about a preference to control storage.sync syncing independently of add-ons, but does not mention its exact name. Does it exist? What is it called?

Comment 3

[Mark Hammond [:markh] [:mhammond] [PTO until Sept 7]]

(In reply to Yuri Khan from comment #2)
> I would call it a documentation bug at least.

I agree we should document this better.

> Also, bug 1290440 speaks about a preference to control storage.sync syncing
> independently of add-ons, but does not mention its exact name. Does it
> exist? What is it called?

services.sync.engine.extension-storage.force - a boolean. If it has a value, that value will be used. If it has no value (the default), then the state of the "addons" checkbox is used.

Comment 4

[Andy McKay]

Docs updated: https://developer.mozilla.org/en-US/Add-ons/WebExtensions/API/storage/sync