The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9c3fdc0b1260b65a3612a016526f4c6fdf043843

commit 9c3fdc0b1260b65a3612a016526f4c6fdf043843
Author: Esmael El-Moslimany <aee@chromium.org>
Date: Tue Mar 27 22:38:10 2018

Settings WebUI: Use proper paper-icon-button-light syntax in protocol handlers.

Bug:  825445 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: Ie0c356ff27d09f3d18ddc90cf2be359f2722351f
Reviewed-on: https://chromium-review.googlesource.com/982384
Commit-Queue: Esmael El-Moslimany <aee@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Reviewed-by: Hector Carmona <hcarmona@chromium.org>
Cr-Commit-Position: refs/heads/master@{#546298}
[modify] https://crrev.com/9c3fdc0b1260b65a3612a016526f4c6fdf043843/chrome/browser/resources/settings/site_settings/protocol_handlers.html

Tested this issue on Windows 10 with chrome #67.0.3382.0 
test url - https://mail.google.com/mail/ 

Steps Followed:
1. while clicking on the service handler
2. Select Allow or Deny
3. Navigate to chrome://settings/handlers?search=handler

Observations:
1. observed test url entry under mailto section
2. Didn't see any blocked section in chrome://settings/handlers

Attaching the screen-cast for reference

aee@ Could you please look into it and help us with repro steps to verify the issue from TE end


Thank You...

Deleted: 825445.mp4 1.7 MB

	825445.mp4 1.7 MB View Download

I can verify that this is working (see screenshot).

@kkaluri:
I also tried the repro steps you posted, and observe what you observed. If you select "Ignore" instead of "Deny", the protocol handler will appear in the "Blocked" section. I don't know whether "Deny" vs "Ignore" works as expected, but that is unrelated to the bug fixed here.

Deleted: paper_icon_button_fixed.png 33.7 KB

	paper_icon_button_fixed.png 33.7 KB View Download