Prevent search suggestions from clipboard text

[simonhong]

fix brave/brave-browser#40415

It's hard to know whether current omnibox input is from clipboard past.
So, prevent search suggestion if current input is same with clipboard text.

Resolves

Submitter Checklist:

• I confirm that no security/privacy review is needed and no other type of reviews are needed, or that I have requested them
• 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 wiki
  • npm run presubmit wiki, 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/Web-Compatibility-Exceptions-in-Brave
  • https://github.com/brave/brave-browser/wiki/QA-Guide
  • https://github.com/brave/brave-browser/wiki/P3A

Test Plan:

BraveSearchProviderTest.DontSendClipboardTextToSuggest

1. Enable search Improve search suggestions in brave://settings/search
2. Copy any text(we call it text1) to clipboard
3. Paste it in omnibox and check search suggestions are not visible for text
4. Copy another text(text2) to clipboard to clear text1 from clipboard
5. Manually type text1 to clipboard and check search suggestions are visible

[brave-builds]

A Storybook has been deployed to preview UI for the latest push

[simonhong]

@brave/sec-team PTAL!

[LaurenWags]

Verified with

Brave | 1.71.58 Chromium: 128.0.6613.120 (Official Build) nightly (x86_64)
-- | --
Revision | 7a3a37ed14fd65ec58c192c3f10aba7ac70cebaa
OS | macOS Version 13.6.9 (Build 22G830)

Using 1.69.162 Chromium: 128.0.6613.120 with "Improve search suggestions" enabled under brave://settings/search, reproduced copy/pasted text into the omnibox showing search suggestions.

1. Using 1.69.162, enabled search Improve search suggestions in brave://settings/search

2. Copied any text(we call it text1) to clipboard
3. Paste it in omnibox and saw search suggestions were visible for text1:

Using 1.71.58 Chromium: 128.0.6613.120, verified test plan from #25118 (comment). Confirmed copy/pasted text into the omnibox does not show search suggestions.

1. Confirmed Show search suggestions was enabled under brave://settings/search (as I'm in a region with Brave Search as default)

2. Copied text (we call it text1) to clipboard
3. Pasted text in omnibox and confirmed search suggestions are not visible for text1

4. Copied other text (text2) to clipboard to clear text1 from clipboard
5. Manually typed text1 to clipboard and confirmed search suggestions are visible