Fixed wrong location bar/omnibox colors are used

[simonhong]

fix brave/brave-browser#22479

This regression comes from below upstream changes.
https://chromium-review.googlesource.com/c/chromium/src/+/3472345

Beforer this change, GetOmniboxColor() is called by ThemeHelper::GetColor()
whereas it's called by ThemeHelper::GetDefaultColor() now.
Then, we get incognito's omnibox color due to our below code at
BraveThemeHelper::GetDefaultColor().

  // Make sure we fallback to Chrome's dark theme (incognito) for our dark theme
  if (type == dark_mode::BraveDarkModeType::BRAVE_DARK_MODE_TYPE_DARK) {
    incognito = true;
  }

  DCHECK(!is_brave_theme_properties);
  return ThemeHelper::GetDefaultColor(id, incognito, theme_supplier);

Fixed by handling omnibox colors before overriding |incognito| var.

Resolves

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:

npm run test brave_browser_tests -- --filter=BraveThemeServiceTest.OmniboxColorTest

[mkarolin]

LGTM 👍

[kjozwiak]

Reproduced the original issue on Win 11 x64 using the following build(s):

Brave | 1.40.7 Chromium: 101.0.4951.41 (Official Build) nightly (64-bit)
-- | --
Revision | 93c720db8323b3ec10d056025ab95c23a31997c9-refs/branch-heads/4951@{#904}
OS | Windows 11 Version 21H2 (Build 22000.613)

Verification PASSED on Win 11 x64 using the following build(s):

Brave | 1.40.8 Chromium: 101.0.4951.41 (Official Build) nightly (64-bit)
-- | --
Revision | 93c720db8323b3ec10d056025ab95c23a31997c9-refs/branch-heads/4951@{#904}
OS | Windows 11 Version 21H2 (Build 22000.613)

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