Mobile Theme: do not display settings when module is inactive.

[jeherve]

Fixes #13385
Fixes #7602

Matching Calypso PR: Automattic/wp-calypso#37857

Changes proposed in this Pull Request:

This PR comes as a first step to deprecate the Mobile Theme feature. We'll start by hiding Mobile Theme Settings from the Jetpack UI when the feature is not active. Folks that still use the feature can access its settings and disable it. Folks who do not use it cannot turn it on via the UI.

The Mobile theme was developed 8 years ago, back when responsive themes weren't a thing. It isn't as useful today, and can even be harmful when one enables it on their site without realizing the consequences, as outlined in #7602.

Is this a new feature or does it add/remove features to an existing part of Jetpack?

• Internal references:
  • p1HpG7-84F-p2
  • p6TEKc-3iM-p2
  • p6TEKc-3jj-p2
  • p6TEKc-3l7-p2

Testing instructions:

• Run yarn docker:wp jetpack module activate minileven to enable the module on your site.
• Go to Jetpack > Settings > Writing.
• Notice that the Mobile Theme settings are there.
• Note that there is now a mention of the upcoming deprecation in the card.
  
• Disable the feature.
• The settings should turn grey and be disabled.
• The settings should also be gone from the old module list.
• When clicking on the "Learn more" link in the notice, the support doc should open in a new window and you should stop a Tracks event if you add localStorage.setItem( 'debug', 'dops:analytics' ); to your browser's console.

Proposed changelog entry for your changes:

• Mobile Theme: disable settings when feature is inactive.

[jetpackbot]

Thank you for the great PR description!

When this PR is ready for review, please apply the [Status] Needs Review label. If you are an a11n, please have someone from your team review the code if possible. The Jetpack team will also review this PR and merge it to be included in the next Jetpack release.

Scheduled Jetpack release: January 14, 2020.
Scheduled code freeze: January 7, 2020

Generated by 🚫 dangerJS against 9f59a81

[ChaosExAnima]

Code works, but the transition is very abrupt- it immediately vanishes when I click off. Can we have it so that it's there till the user refreshes the page, perhaps?

[keoshi]

This works as expected in my testing!

[jeherve]

Code works, but the transition is very abrupt- it immediately vanishes when I click off. Can we have it so that it's there till the user refreshes the page, perhaps?

That's a good point. I am not sure what the best approach would be for this, though. Should we fake the deactivation until they move to a different page, or tab?

[dereksmart]

What if instead of a workaround to leave it for the page session, we just add a line of text to the card - something like:

This feature is being discontinued and will be removed from Jetpack in a future release. If you disable this setting, you will not be able to re-activate it.

[jeherve]

Done in afeb464.

@jeffgolenski How does this look to you?

You should be able to test on Jurassic Ninja as soon as the tests pass on this PR. 👍

[jeffgolenski]

@jeherve That looks good to me. I'd personally like to have a little more visual call-out for this, but I don't think it's worth adding extra code to a component just for this notice. 🚢

[kraftbj]

I agree with @ChaosExAnima that the transition is harsh, but given the overall intent to remove the feature soon, I'm not going to block merging based on that.

[jeffgolenski]

Tested with both the theme already active, and inactive. Works great. Let's ship it.

[kraftbj]

Looks good. No errors in the console.