> I would like to understand a bit better what happens when the user removes a
> google account. My previous understanding is that synchronization of contacts
> would stop working, but the contacts that were imported from the google
> account would remain. Is it correct, or are they removed as well?
> And if the latter, would the contact reappear automatically, if/when the
> account is re-added again?

The contacts and any data synced from this account will be removed.

> 
> Then, about messages: what messages are we talking about? Are we planning to
> integrate with Google XMPP chat?

We are implementing a new framework called "messaging-framework" this framework will run as a telepathy plugin but with Canonical API (we will have some kind o glue code to integrate it with telepathy). Since telepathy is integrated with our history service, all messages will be stored on a system-wide log file. The messages related with this account will be removed as well.

> 
> And last: ordinary (confined) applications cannot distinguish whether an
> account has been removed or just disabled: they just see it disappear. It
> looks like you want to treat these two events differently -- I guess you may,
> since your processes run unconfined. However, I think this would be
> inconsistent with how the rest of the applications work, and ultimately cause
> more confusion to the user.
Yes we do not have control over third party applications. We can not guarantee that the data will be removed. We can not say in the message that all data will be removed.

> 
> 
> I would propose a different approach: when an account is deleted or disabled,
> just stop synchronising contacts and messages, but keep them there. Then, next
> time the user opens the Contacts or Messages application (or maybe when the
> user performs a certain action inside these applications, for example clicking
> the "sync" icon or opening a conversation with an account which no longer
> exists), popup a dialog with something like:
> 
>    You have removed Contacts access to the account <email address hidden>:
>    do you still want to keep old contacts associated with it?
> 
>            Keep               Remove contacts
> 
> And a similar thing for the Messaging app.

Address book app is not a sync app it only contains the sync button because we did not find a way to automatically sync the contacts if the contacts get changed on the service side (the idea is to implement something with push-notification, and remove the button from address-book-app). 
The address-book-app just handle data already synced in the device it should not care about accounts and synchronization.

We have already discussed that with designers, Keeping the contacts/messages/calendar will cause more problems than benefit. If we allow the user to keep the contacts, we will need a interface to give the option to remove it in the future (remove all contacts from a specific account, not removing individual contacts). Another big problem is the case where the user decided to re-add the account, all contacts will be duplicated because the old contacts was liked to the other account, and some others small problems.

All systems (android, IOS) remove the contacts if you remove the account. I believe they do that avoid problems if you decide to add the account again.

In case of message, the old messages became useless since you will not be able to read it anymore since probably the contact will no longer exists. 

For sure we can handle all the cases that I mentioned above, but this will be more complex and consume so many time (designer/engineer) and making everything more confuse for the user. Because of that we decided that does not worth the work. 

> 
> One more option is to have a configuration panel inside the messaging app,
> where you can decide to remove conversations older than XX days. So you
> wouldn't need to ask anything to the user, and the conversations associated to
> a deleted account would automatically be deleted after some time, without the
> user intervention.