🌑Dark theme persists in UI after switching back to Light🌕

[InternetJohnny]

Description

Having enabled 🌑dark theme and gone back to using the 🌕light theme, some elements of the UI remain themed dark🌑 - settings dropdown, permissions alert box (notifications, location, etc) - while the address bar and tabs have the proper 🌕light theme.

Steps to Reproduce

1. Switch to dark theme 🌑
2. Switch back to light theme 🌕

Actual result:

Expected result:

Consistent theme throughout the UI (either all dark or all light)

Reproduces how often:

Happens every time on my laptop and not at all on my desktop (quite weird because I installed the same version of the Beta, from scratch, on both machines.

Brave version (brave://version info)

Brave	0.63.34 Chromium: 74.0.3729.40 (Official Build) beta (64-bit)
Revision	278d6a0d856d8314f36fb9a68b6e1d85cd0d14e7-refs/branch-heads/3729@{#470}
OS	Windows 10 OS Build 17763.379
JavaScript	V8 7.4.288.13

Reproducible on current release:

• Does it reproduce on brave-browser dev/beta builds?
  It is happening on the Beta for me

Website problems only:

• Does the issue resolve itself when disabling Brave Shields?
  No
• Is the issue reproducible on the latest version of Chrome?
  Chrome does not have a dark theme

Additional Information

[bsclifton]

cc: @petemill @simonhong

[InternetJohnny]

Ok, so I actually managed to find out a bit more about its behavior.

It seems like every element of the Brave UI - except for the address/tabs bar at the top - follows (is controlled by) the Windows setting for the UI theme (dark/light).

Basically, if your Brave theme is set to 'light' 🌕, but the Windows theme is set to 'dark' 🌑, your addres/tabs bar will be light, but the rest of the Brave UI will be dark.

Here's an example of this:

[rebron]

cc: @srirambv to try to reproduce on Windows.

[simonhong]

Aligning base UI theme(ex, context menu) with brave theme is not implemented on Windows for now.
On MacOS, we did this by changing app appearance when brave theme and OS theme are different.
With this, we can use different app appearance than MacOS theme.
However, we can't apply this approach on Windows because Windows doesn't support per-app appearance. Need to find different approach for Windows.

[btlechowski]

Verification passed on

Brave	0.66.87 Chromium: 75.0.3770.80 (Official Build) beta (64-bit)
Revision	9a9aa15057b6b2cc0909bdcf638c0b65ecd516f2-refs/branch-heads/3770@{#948}
OS	Windows 10 OS Version 1809 (Build 17763.379)

Verified test plan from brave/brave-core#2352 and from the description. Checked changing Light->Dark mode and Dark->Light mode. Checked settings dropdown, permissions alert box (notifications, geolocation, translations, alerts) and downloads bar. Also checked Same as Windows option.