Version: 55.0.2859.0
OS: Ubuntu 14.04,Windows

What steps will reproduce the problem?
(1)Launch chrome -> Sign into Profile-> click on avatar icon 
(2)Now click on 'Switch person' option for User Manager window-> Select 'ADD PERSON' ->Now Check the 'Supervise this person...' checkbox 
(3)Click on 'SAVE' Button ->'Select an account to manage the supervised user' Alert Message is displayed -> Now select an account from Drop down and observe Alert Message(pLease refer Video)

Expected: Alert Message should get  disappeared after selecting the account from Drop down 
Actual: Instead Alert Message is not disappeared 


This is Non-Regression Issue  as Alert Messages are introduced from 51.0.2704.0

Below is the MANUAL CHANGELOG URL:
https://chromium.googlesource.com/chromium/src/+log/51.0.2702.0..51.0.2704.0?pretty=fuller&n=10000

Suspecting https://codereview.chromium.org/1826903002  from Manual Changelog

@mahmadi : Please feel free to re-assign if its not related to your change
 

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