Private Windows' info boxes don't auto-expand to fill up empty space

[stephendonner]

Description

Private Windows' info boxes don't auto-expand to fill up empty space

(Found while testing #22566.)

Steps to Reproduce

1. install 1.43.13
2. launch Brave
3. open a new Private Window
4. open a new Private Window with Tor
5. constrain the window sizes of both to their smallest width
6. look at the "info box" below the search bar

Actual result:

The info box doesn't auto-expand its width to fill up the space (as the search bar correctly does).

Private Window	Private Window with Tor

Expected result:

The info box's width should auto-expand, a la the search box above it.

Spec (Figma):

Reproduces how often:

100%

Brave version (brave://version info)

Brave	1.43.13 Chromium: 103.0.5060.114 (Official Build) nightly (x86_64)
Revision	a1c2360c5b02a6d4d6ab33796ad8a268a6128226-refs/branch-heads/5060@{#1124}
OS	macOS Version 13.0 (Build 22A5295i)

Version/Channel Information:

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

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields?
• Does the issue resolve itself when disabling Brave Rewards?
• Is the issue reproducible on the latest version of Chrome?

Miscellaneous Information: