[Desktop] #extensions-toolbar-menu no longer works when enabled after update to v1.10.90

[Brave-Matt]

Description

Brave update to v1.10.90 breaks the #extensions-toolbar-menu flag. When the flag is enabled, the Extension toolbar menu shows, but all the extensions still appear on the toolbar:

Steps to Reproduce

1. Launch Brave and visit brave://flags
2. Search for and enable the #extensions-toolbar-menu flag.
3. Relaunch the browser and note that extensions still appear on the toolbar

Actual result:

[See image above] Extensions continue to appear on toolbar (and in extension menu)

Expected result:

Extensions should appear only in the menu while the flag is enabled.

Reproduces how often:

Always

Brave version (brave://version info)

Brave	1.10.90 Chromium: 83.0.4103.97 (Official Build) (64-bit)
Revision	326d148b9655369b86498d9ecca39f63dd2bdd2d-refs/branch-heads/4103@{#657}
OS	macOS Version 10.15.5 (Build 19F101)

Version/Channel Information:

• Can you reproduce this issue with the current release? Yes
• Can you reproduce this issue with the beta channel? Yes
• Can you reproduce this issue with the dev channel? Yes
• Can you reproduce this issue with the nightly channel? Yes

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields? N/A
• Does the issue resolve itself when disabling Brave Rewards? N/A
• Is the issue reproducible on the latest version of Chrome? No.

Miscellaneous Information:

I was able to reproduce this on Linux, Windows and macOS.
Original user report: https://community.brave.com/t/todays-brave-update-extensions-toolbar-menu-not-working/135501

[rebron]

Considering to wontfix this as this is a chrome flag and not a supported feature.