App Version: 71.0.3578.57 Beta
iOS Version: 11.4.1, 12.0.1, 12.1.1 beta #2
Device: iPhone and iPad                                                                                                                                                                                                                                                                            

Steps to reproduce:
1. Launch chrome in portrait
2. Visit wikipedia.org or any pdf file 
3. Scroll the page and stop at certain position
4. Change the device orientation to landscape

Observed results:
Notice that web page position is not retained at step 3 scrolled position 

Expected results:
Web page position should be retained on changing the device orientation

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:

Chrome behavior:
https://drive.google.com/file/d/1_g5Q6gSDUoC2WfHCVT9R-C7m1nBfYb7k/view?usp=sharing

Safari Behavior:
https://drive.google.com/file/d/1-0QfRNIQ5KjTG9yL3eFUAgLAD261feE-/view?usp=sharing