Remove duplicated menu separator after remove translate menu item

[AlexeyBarabash]

Resolves brave/brave-browser#15714

Sometimes after removing the Translate menu item, separator item is duplicated.
This PR removes the duplicated separator, if required.

Not related to the sync options on Nightly 1.27.4 at least.

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
• 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. Open the website of other language than your system has
2. Invoke the context menu
3. Ensure there are no double separators one by one, as on Double separator line when you can "send to Google phone" brave-browser#15714 screenshots.

[bridiver]

is this helpful here? It was recently added https://chromium.googlesource.com/chromium/src.git/+/3ac3f99cb82b34690d800a4dfdbefe2630060e39%5E%21/

[AlexeyBarabash]

@bridiver ,
42c0333
yes, there are two useful methods: RenderViewContextMenuBase::RemoveSeparatorBeforeMenuItem and RenderViewContextMenuBase::RemoveAdjacentSeparators.

RemoveAdjacentSeparators may be used in the end of BraveRenderViewContextMenu::InitMenu() to exclude any possibility of duplicating the separators.

Both RemoveSeparatorBeforeMenuItem and RemoveAdjacentSeparators have the code in the end

  if (toolkit_delegate_)
    toolkit_delegate_->RebuildMenu();

But toolkit_delegate_ is initialized after BraveRenderViewContextMenu::InitMenu(), so I had to clear and restore toolkit_delegate_ to avoid the crash.

[AlexeyBarabash]

CI failed, needs rebase

[AlexeyBarabash]

CI failed on gn_check, related to the PR

[yrliou]

LGTM as long as we pass the test plan in #3103.

[yrliou]

LGTM

[simonhong]

@AlexeyBarabash Can you check this condition again?
I think below views related sources should be included with toolkit_views condition above.
|use_aura| is false for macOS.