remove CallJavascriptFunctionUnsafe from brave://adblock webui

[antonok-edm]

Resolves brave/brave-browser#15638

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:

[kkuehlz]

LGTM. I have found several examples in Chromium where they follow this exact pattern.

Obviously not expected in this PR, but it looks like this method is a wrapper around a dispatcher.

brave-core/components/brave_adblock_ui/brave_adblock.tsx

Lines 41 to 44 in f17c1fb

	function onGetCustomFilters (customFilters: string) {
	const actions = bindActionCreators(adblockActions, store.dispatch.bind(store))
	actions.onGetCustomFilters(customFilters)
	}

A future improvement would be registering the webUIListenerMap with the JS callback, and notify it using WebUIMessageHandler::FireWebUIListener (this is what the safebrowsing example I linked does. More info here). It could also promisified and then C++ can resolve it with ResolveJavascriptCallback(..).