Dark mode for new tabs page settings

[imptrx]

Description

New tabs page's settings menu should adjust itself based on the user's currently set theme, whether it be Light, Dark or the theme set on the OS level.
Currently, the settings menu will look the same no matter what.

Design

The Dashboard Settings menu should support dark theme set at the OS level:

[GeetaSarvadnya]

Verification passed on

Brave	0.70.97 Chromium: 77.0.3865.65 (Official Build) beta (64-bit)
Revision	87a331a3169cab563505fb44011058b904011ba1-refs/branch-heads/3865@{#726}
OS	Windows 10 OS Version 1803 (Build 17134.1006)

• Verified the test plan from New Tabs Page: Enable NTP to be theme aware brave-core#3115

[btlechowski]

This issue is still reproducible on 0.69.128

It is not reproducible on 0.70.99

Tested Windows and Linux.

@kjozwiak I suggest we move the milestone to 0.70.x

[kjozwiak]

Seeing the same thing as @btlechowski as per #5014 (comment). @rebron @bsclifton do know if this landed in 0.69.x? As @btlechowski mentioned, the fix seems to be working under 0.70.99 CR: 77.0.3865.90 but not under 0.69.128 CR: 77.0.3865.75. Example:

Using 0.69.128 CR: 77.0.3865.75:

Using 0.70.99 CR: 77.0.3865.90:

[cezaraugusto]

changing milestones as this work landed only in 0.70.x cc @kjozwiak

[LaurenWags]

Verified passed with

Brave	0.70.110 Chromium: 77.0.3865.90 (Official Build) beta (64-bit)
Revision	58c425ba843df2918d9d4b409331972646c393dd-refs/branch-heads/3865@{#830}
OS	macOS Version 10.13.6 (Build 17G5019)

• Verified test plan from New Tabs Page: Enable NTP to be theme aware brave-core#3115 on High Sierra (no OS level dark mode)

• gifs in Dark mode for new tabs page settings #5014 (comment) show the fix for this issue on Mojave from @kjozwiak

Verification passed on

Brave	0.70.109 Chromium: 77.0.3865.90 (Official Build) beta (64-bit)
Revision	58c425ba843df2918d9d4b409331972646c393dd-refs/branch-heads/3865@{#830}
OS	Ubuntu 18.04 LTS

• Verified test plan from New Tabs Page: Enable NTP to be theme aware brave-core#3115

Dark mode

Light mode

Verification passed on

Brave	0.70.111 Chromium: 77.0.3865.90 (Official Build) beta (64-bit)
Revision	58c425ba843df2918d9d4b409331972646c393dd-refs/branch-heads/3865@{#830}
OS	Windows 10 OS Version 1803 (Build 17134.1006)

• Verified test plan from New Tabs Page: Enable NTP to be theme aware brave-core#3115

Dark mode:

Light mode: