App Version: 71.0.3578.23 Beta
iOS Version: 12.0, 11.4.1, 10.3.3, 12.1 beta 5
Device: iPhone only

Steps to reproduce:
1.Launch chrome app 
2.Load any web page eg: wikipedia.org
3.Scroll the screen to perform Pull to refresh
4.Tap immediately on omnibox next to title

Observed results:
Tab page closes

Expected results:
Tab page shouldn’t close

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: Not tested
Bug reproducible on Safari/Firefox: Firefox: No, Safari: No
Bug reproducible on current stable build (App Version, iOS Version): Yes on M70
Bug reproducible on the current beta channel build (App Version, iOS Version): Yes on M71 Beta

Link to video:
https://drive.google.com/file/d/1-YGyx41UoX-Q2QBNCkizTmIezVJbjEkn/view?usp=sharing