Clock on new tab page in wrong format (should be same format as system)

[Jamesking56]

Description

Clock on new tab page does not respect OS time format

Steps to Reproduce

1. Set system time format to 12-hour (AM/PM in Ubuntu Settings)
2. Open Brave new tab page
3. See clock is not in 12-hour format

Actual result:

Clock is not respecting system time format

Expected result:

Clock should be in the same format as system time

Reproduces how often:

Easily reproduced

Brave version (brave://version info)

Brave	1.2.43 Chromium: 79.0.3945.130 (Official Build) (64-bit)
Revision	e22de67c28798d98833a7137c0e22876237fc40a-refs/branch-heads/3945@{#1047}
OS	Linux

OS says Linux but I am running Ubuntu 18.04 LTS

Version/Channel Information:

Only tried on current channel.

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? Not sure how to test

Miscellaneous Information:

[sethasaurus]

Can't believe this is not resolved yet! WTAF guys?

[JonasNo]

Because they don't care! It they cared we would have an option already to switch between am/pm and proper 24hour clock.

[bsclifton]

As a follow up to #9038 (which has a PR open: brave/brave-core#6667), the solution for this would be to get the time in the browser process (in a message handler) and fetch from the JavaScript side. That would ensure it uses the same time as the sytem (ex: use base/time/time.h)

Currently, Intl.DateTimeFormat is being used; initialized with whatever locale JavaScript is detecting (by default, I think via accept-language headers). This is different than the system time for a lot of folks