[dialer-app] contacts view should remember state

[Gabriele]

Step to replay:

- Open the phone app;
- Do a tap to the contacts icon in the top right corner;
- Do research and choose a contact with multiple phone numbers;
- Do a tap on one of the numbers -> you return to the phone app and you are ready to be a call;
- There is no direct way to return to the previous contact card opened (for example to change number if it is busy or to call alternative number) without repeating the search again.

It would be useful to have a button to return to the phone app that makes return to the open contact to call a different number (or send an SMS / e-mail)

------ UX comment -------

The solution is as follows:
1. open dialer
2. tap on the contacts in the top right corner in the header
3. find a contact and tap it to go into the contact card
4. tap a number to call
5. view returns to the dialer with the pre-populated number
6. do not tap call!
7. now tap again the contacts icon in the top right corner in the header
8. view should show you the previously opened contacts card

Additional desired behaviours:
If user taps the back button in the contact card, screen goes back to list of contacts.
If user initiated a call, then tapping the back button from the calling screen goes back to the keypad (indicator bar turns green, to show user there is an active call happening). A tap on the contacts icon in the top right corner in the header from this view shows user the last opened contact card.

Please refer to this spec for the latest UX:
https://docs.google.com/document/d/1BRy9-DEXr3A1D7PHkJaXmjbe7xbRmxKkzANXuu-F6lc/edit

[Olga Kemmet (olga-kemmet)]

Bug description contains desired solution, hence marking as Fix Committed from design.

[Renato Araujo Oliveira Filho (renatofilho)]

I am used to android and if I call a busy or invalid number, I open the recent list and access the last called contact from there and then I can choose a new number.

The proposal solution breaks how a PageStack works. The pageStack implementation destroy the contact detail and the contact list page as soon as you click to call the contact, and goes back to the initial page that is the dialer page.

We could store the previous state and try to restore it if the use click on the contact button, but this can bring some weird states, for example :

The user tap to call a contact and the call was successful, he leaves the app without close it and after a while he tap on contacts button to make a new call or add a new contact, it will have a saved state and will try to reload both pages contact list, and contact view to keep it consistent (the page path is dialer->contact list->contact view)

Restoring the state can cause error for example if the contact was deleted/edit.