Chrome Version (from the about:version page): 57.0.2987.123
Is this the most recent version: Yes
OS + version: Ubuntu - modified build
CPU architecture (32-bit / 64-bit): 64-bit
Window manager: N/A
URLs (if relevant): https://www.chromium.org/administrators/configuring-other-preferences
Behavior in Linux Firefox: N/A
Behavior in Windows Chrome (if you have access to it): N/A

What steps will reproduce the problem?
(1) Open the Chrome browser

What is the expected result?
Chrome Browser opens the homepage specified in the policies (json file) 

What happens instead?
Chrome Browser opens a sign in tab

Please provide any additional information below. Attach a screenshot
and backtrace if possible. 
The customer has a modified build of Ubuntu in the school, there policies are set via json file, and there is a script that erase all the local content. When the users open the browser  it always ask to sing in, the sign in is restricted in the json file, but the customer does not want that sign in page showing up every time.