[Desktop] Remove Sync from brave://settings under Tor/Guest Windows

[kjozwiak]

Description

We should remove the Sync option from brave://settings for Tor/Guest windows as sync shouldn't be used while Tor/Guest mode is being used. Preferences that are accessed via the hamburger menu or the file menu are opened in regular tabs but this prevents users from accessing the preferences via brave://settings and clicking on brave://sync.

Steps to Reproduce

1. launch brave (0.60.13 Chromium: 72.0.3626.53 in this instance)
2. open a Tor/Guest window and visit brave://settings
3. notice that the Sync area is being displayed/accessible

Actual result:

Expected result:

Sync section under brave://settings shouldn't be visible/accessible under Tor/Guest

Reproduces how often:

100% Reproducible

Brave version (brave://version info)

Brave	0.60.13 Chromium: 72.0.3626.53 (Official Build) dev(64-bit)
Revision	98434e6cd182d68ce396daa92e9c6310422e6763-refs/branch-heads/3626@{#620}
OS	Mac OS X

Reproducible on current release:

• Does it reproduce on brave-browser dev/beta builds?

Reproducible wherever sync is enabled.

Additional Information

[kjozwiak]

Just a heads up to @brave/legacy_qa, the Tor case isn't valid anymore as we don't open brave://settings in Tor windows. When a user attempts to open brave://settings in Tor, we either change focus on a tab that already has the settings page opened or create a new brave://settings tab in a normal window.

[kjozwiak]

Verification PASSED on macOS 10.15.5 x64 using the following build:

Brave | 1.11.92 Chromium: 84.0.4147.68 (Official Build) dev (64-bit)
-- | --
Revision | e7b7234037639b407e69c5428c891ce018cd6c0d-refs/branch-heads/4147@{#772}
OS | macOS Version 10.15.5 (Build 19F101)

• ensured that Sync isn't available under the Hamburger menu under Guest windows
• ensured that Sync isn't visible under brave://settings under Guest windows

---

Verification passed on

Brave | 1.11.92 Chromium: 84.0.4147.68 (Official Build) dev (64-bit)
-- | --
Revision | e7b7234037639b407e69c5428c891ce018cd6c0d-refs/branch-heads/4147@{#772}
OS | Windows 10 OS Version 1903 (Build 18362.900)

• ensured that Sync isn't available under the Hamburger menu under Guest windows
• ensured that Sync isn't visible under brave://settings under Guest windows
  
  

---

Verification passed on

Brave	1.11.92 Chromium: 84.0.4147.68 (Official Build) dev (64-bit)
Revision	e7b7234037639b407e69c5428c891ce018cd6c0d-refs/branch-heads/4147@{#772}
OS	Ubuntu 18.04 LTS

• ensured that Sync isn't available under the Hamburger menu under Guest windows
• ensured that Sync isn't visible under brave://settings under Guest windows