App Version: 65.0.3325.53 Beta
iOS Version: 11.2.2
Device : iPhone X only
Url : youtube.com

Steps to reproduce : 
1. Launch chrome in landscape mode  
2. Play any video
3. Send the chrome to background while video is playing.
4. Relaunch chrome in portrait mode.

Observed results:
White patch is displayed and youtube video is misaligned.

Expected results:
Youtube video should fit in the screen size.

Note : Works fine on enabling Safari User agent

Number of times you were able to reproduce: 3/5
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: Works fine in safari and firefox
Bug reproducible on current stable build (App Version, iOS Version):  Yes in M64
Bug reproducible on the current beta channel build (App Version, iOS Version): Yes in M65

Link to Video :
https://drive.google.com/file/d/1LtsXpM3lWT_WFBi0Zm9xj1uI-bMQ0lcQ/view?usp=sharing