App Version: 70.0.3538.60 beta
iOS Version: 11.4.1, 12.0.1
Device: iPhones, iPads
URL: Chrome Settings -- NTP

Steps to reproduce:
  1.  Launch chrome beta.
  2.  Go to Chrome Menu --> Incognito tab --> Open 7 incognito tabs on iPhones/ open 11 incognito tabs on iPads
  3.  In the 8th incognito tab open “Help” page for iPhones  (Go to Menu --> Chrome Menu --> Help) / In the 12th incognito tab open “Help” page for iPads 
  4.  Tap on Tab switcher button 

Observed results:
Notice that open new tab “+” button is not visible when the background has a white color

Note: Can clearly notice the issue if the device brightness is 50%.

Expected results:
Open new tab “+” button color should be in contrast with the background color

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 Safari/Firefox: Firefox: NA, Safari: NA
Bug reproducible on current stable build (App Version, iOS Version): Yes on M69
Bug reproducible on the current beta channel build (App Version, iOS Version): Yes on M70

Link to video/image:  https://drive.google.com/file/d/1EkFHVD7PdG3aBHA-k9WpIFOFxZeLkQbI/view?usp=sharing