App Version: 63.0.3239.27 beta
iOS Version:10.3.3, 11.0.1
Device : iPhone,iPad

Precondition.
1- Have 2 to 3 accounts in SSO

Steps to reproduce : 
1. Launch chrome and sign in chrome with Account A.
2. Tap on Menu > Settings > Select the signed in user.
3. Tap on Sync > Tap on Encryption > Tap on Encrypt all synced data.
4. Send the app to background in Create passphrase screen.
5. Launch SSO app or Chrome Canary.
6. Add or Remove any Account B in Chrome canary.
7. Relaunch chrome beta > Tap on Settings in You’re signed in screen
8. Tap on Sign out of chrome. 

Observed results:
App Freezes

Expected results:
App should not freeze

Number of times you were able to reproduce: 5/5
Bug reproducible after clean install: Yes
Bug reproducible after clearing cache and cookies: Yes
Bug reproducible on Chrome Mobile on Android: NA
Bug reproducible on Dolphin/Safari/Firefox: Safari : NA
Bug reproducible on current stable build (App Version, iOS Version): Yes in M62
Bug reproducible on the current beta channel build (App Version, iOS Version): Yes in M63

Link to video :
https://drive.google.com/a/google.com/file/d/1PLFUuLlN_59K0CZ8Qg6YsK5yNdyIjO9p/view?usp=sharing