Chrome Version: 73.0.3664.3 (Official Build) cac0e5b7d469aad82d6fd21ee684caeec1c5cf46-refs/branch-heads/3664@{#5}(32/64 bit)
OS: Win(7,8,8.1,10) ,Mac(10.13.1 , 10.13.6 , 10.14.3)and Linux(14.04 LTS).

Pre-condition:
Enable following flags under chrome://flags
-Identity consistency between browser and cookie jar.
-Unified Consent

Steps to reproduce:
1. Launch chrome and Sign-in chrome with valid credentials.
2. On Sign-in overlay click on 'Settings' ,which will navigate to chrome://settings/syncSetup.
3. Observe 'Turn off' button on chrome://settings/syncSetup page.
 
Actual Result   : 'Turn off' button is disabled on chrome://settings/syncSetup.
Expected Result : 'Turn off' button should be enabled on chrome://settings/syncSetup.

This is a regression issue broken in M-73 and will below is the bisect information:
Good Build :73.0.3645.0 (Revision: 618066)
Bad Build : 73.0.3646.0 (Revision: 617714)

Change Log:
https://chromium.googlesource.com/chromium/src/+log/73.0.3645.0..73.0.3646.0?pretty=fuller&n=10000

Suspect:r 617793?

@Thomas Tangl: Could you please check whether this is caused with respect to your change, if not please help us in assigning it to the right owner.

Note: 
1. Unable to provide 'per-revision' bisect as it shows "We don't have enough builds to bisect" error message for above range. (tried on other machines but still getting the same error again)
2. Hence providing suspect from change-log as Sign-in chrome is not available in chromium builds.

Kindly refer the attached screen-cast from drive link.
https://drive.google.com/open?id=1cPyQTFMkwFkdzbO_kanECnnq7CpDz_qs

Thank You.