cleanup resources file handling

[bridiver]

requires brave/brave-core#566
fix #1419

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Verified that these changes build without errors on
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• Verified that these changes pass automated tests (npm test brave_unit_tests && npm test brave_browser_tests) on
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• Ran git rebase master (if needed).
• Ran git rebase -i to squash commits (if needed).
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• Requested a security/privacy review as needed.

Test Plan:

Reviewer Checklist:

• New files have MPL-2.0 license header.
• Request a security/privacy review as needed.
• Adequate test coverage exists to prevent regressions.

[yrliou]

Please also remove these copies in https://github.com/brave/brave-browser/blob/master/lib/util.js#L114-L117, and variables which become unused after you remove this.

[yrliou]

LGTM, thanks!