"Suspicious site ahead" blocked-content warning message appears for ads

Description

“Suspicious site ahead” blocked-content warning message appears for ads

Steps to Reproduce

1. new profile (not necessary, but a good idea, for default settings)
2. load https://apps.facebook.com/wordswithfriends
3. log in using Facebook credentials
4. wait for page to load
5. click on the Shields icon in the URL bar and disable Shields

Actual result:

Expected result:

Reproduces how often:

100%

Brave version (brave://version info)

Reproduces in:

Brave	1.24.14 Chromium: 89.0.4389.90 (Official Build) nightly (x86_64)
Revision	62eb262cdaae9ef819aadd778193781455ec7a49-refs/branch-heads/4389@{#1534}
OS	macOS Version 11.2.3 (Build 20D91)

(and current beta and dev channels)

Version/Channel Information:

• Can you reproduce this issue with the current release? no
• Can you reproduce this issue with the beta channel? yes
• Can you reproduce this issue with the nightly channel? yes

cc/ @ryanbr @antonok-edm @pes10k (sorry for casting the net wide)

[pes10k]

I believe @antonok-edm and @pilgrim-brave are handling this here: https://github.com/brave/brave-browser/issues/14826

[rebron]

@stephendonner Looks like we can just dupe to #14826