Private tabs is lost during migration update when app is in background

[srirambv]

Description:

Private tabs is lost during migration update when app is in background

Steps to Reproduce

1. Set 1.6.6 to be on normal tabs
2. Open a couple of private tabs and visit sites in them
3. Background the app and upgrade to 1.7
4. After upgrade launch, pin is enabled(#566) and private tabs opened are lost, focus is set to first normal tab

Actual result:
Private tabs is lost during migration update when app is in background

Expected result:
Should retain the private tabs that were active when app was still in memory

Reproduces how often: [Easily reproduced, Intermittent Issue]
Easy

Brave Version:
1.7 (18.12.04.23)

Device details:
iPhone and iPad

Website problems only:

• did you check with Brave Shields down?
• did you check in Safari/Firefox (WkWebView-based browsers)?

Additional Information

[jhreis]

This is expected behavior. This is basically a desktop browser upgrade, where it has to quit the app to upgrade. Since we don't save private browsing data, these cannot be recovered.