Show connection error view if network unavailable

[spylogsster]

Resolves brave/brave-browser#22754

Brave.Browser.Development.-.New.Tab.-.3.June.2022.mp4

Checking network adapters status before setting internal connection status and correct it if no network access.

Submitter Checklist:

• I confirm that no security/privacy review is needed, or that I have requested one
• There is a ticket for my issue
• Used Github auto-closing keywords in the PR description above
• Wrote a good PR/commit description
• Squashed any review feedback or "fixup" commits before merge, so that history is a record of what happened in the repo, not your PR
• Added appropriate labels (QA/Yes or QA/No; release-notes/include or release-notes/exclude; OS/...) to the associated issue
• Checked the PR locally: npm run test -- brave_browser_tests, npm run test -- brave_unit_tests, npm run lint, npm run gn_check, npm run tslint
• Ran git rebase master (if needed)

Reviewer Checklist:

• A security review is not needed, or a link to one is included in the PR description
• New files have MPL-2.0 license header
• Adequate test coverage exists to prevent regressions
• Major classes, functions and non-trivial code blocks are well-commented
• Changes in component dependencies are properly reflected in gn
• Code follows the style guide
• Test plan is specified in PR before merging

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on
• All relevant documentation has been updated, for instance:
  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protections
  • https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • https://github.com/brave/brave-browser/wiki/Custom-Headers
  • https://github.com/brave/brave-browser/wiki/Web-Compatibility-Exceptions-in-Brave
  • https://github.com/brave/brave-browser/wiki/QA-Guide
  • https://github.com/brave/brave-browser/wiki/P3A

Test Plan:

1. Complete the steps under Brave Premium login > Login to an existing account which has VPN
2. Unplug your network cable (or disable Wi-Fi)
3. Click the VPN button (top right, next to hamburger button)
4. Click the toggle to ENABLE
5. You should see the error about not being able to connect
6. Plug network cable back in OR enable Wi-Fi (disabled in step 2)
7. Click the Try again button
8. It should work now

[simonhong]

How about early return when network is unavailalbe in the Connect() instead of going normal path?

[simonhong]

How about moving this include to below #if !BUILDFLAG(IS_ANDROID) as it's used in non-android code?
and this include doesn't need to add //net to deps list?
Hmm, already we've included net's headers below. Curious why gn_check doesn't complain about it.
Maybe it's allowed by public_deps of other deps? :)
I think just adding //net to deps explicitely is sufficient.

[spylogsster]

done

[spylogsster]

How about early return when network is unavailalbe in the Connect() instead of going normal path?

done

[simonhong]

++

[spylogsster]

Failed tests are not replated to this PR