Explicitly pass application locale to GetUILanguageList

Currently, it internally uses g_browser_process->GetApplicationLocale()
to get the app locale. Although the locale string should only be
accessed on the UI thread, there is a place where GetUILanguageList is
called from other threads.

This CL changes the function to explicitly take the app locale string
so that it can be called from other threads.

Bug: 403155091
Change-Id: I4c661ed6ab0f0abbc89ec7d7d6bc8de4ee96929b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6399494
Commit-Queue: Jun Ishiguro <junis@google.com>
Reviewed-by: Hidehiko Abe <hidehiko@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1439154}