App Version: 65.0.3319.0 canary 
iOS Version: 11.0.1
Device : iPhone X

Steps to reproduce : 
1. Launch chrome in landscape mode.
2. Tap on Menu > Settings > Sign in to chrome/Add account.
3. Tap on Username
4. Send the app the background
5. Relaunch chrome in Portrait mode.

Observed results:
Done button truncates with keyboard

Expected results:
Done button should not truncate

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 M63
Bug reproducible on the current beta channel build (App Version, iOS Version): Yes in M64

Link to video :
https://drive.google.com/file/d/1RKvHhb2HbjPvnzqGL_fUNe7dVr1k3IF2/view?usp=sharing