Add DebounceService for iOS

[cuba]

Resolves brave/brave-browser#33275

Expose the debounce service to iOS. In order to do this a couple of things had to be done:

1. Separate core and common debounce component code so only the usable parts are exposed to iOS
2. Create a debounce service factory for iOS
3. Create a iOS objc API interface for iOS

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 lint, 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/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:

[bridiver]

shouldn't we just expose a generic interface to prefs? cc @Brandon-T

[cuba]

I followed along other examples we had but I agree some generic approach would be perhaps nicer.

[bridiver]

can we look at this in a follow-up?

[cuba]

Personally I think it's a good idea. But while I opened up some discussion around a generic approach there was no conclusive decision about this. Im willing to re-open this discussion more openly.

[kylehickinson]

iOS++

[bridiver]

missing newline here. I recommend configuring your editor to always add it

[cuba]

@bridiver I removed a bunch of unneeded imports. But as stated is there a mechanism in which I can detect unused imports or is it just a manual process of cross referencing imports with code usage?

[ShivanKaul]

@bridiver I removed a bunch of unneeded imports. But as stated is there a mechanism in which I can detect unused imports or is it just a manual process of cross referencing imports with code usage?

We've discussed adding automation for this but AFAIK we don't have anything just yet.

[github-actions]

[puLL-Merge] - brave/brave-core@20315

Description

This PR refactors the debounce component by moving it to a new subdirectory (core) within its module, affecting various parts of the codebase where the debounce component is integrated or utilized. The aim seems to be to reorganize the code for better modularity or clarity, grouping core functionality distinctly.

Changes

Changes

• Component Move & Namespace Changes: Refactored the structure of the debounce component, moving files from components/debounce/browser and components/debounce/common to components/debounce/core/browser and components/debounce/core/common respectively.

  • Major filename changes and path adjustments reflect this structure change across the codebase.
  • Updated include statements in various files to the new paths.

• Build Configuration Updates: Altered paths in .gn files to accommodate the new directory structure. Updated dependencies in BUILD.gn files across various targets to reflect the moved debounce component files.

• Code Modifications:

  • Updated file headers from block comments to line comments for consistency.
  • Minor code style and formatting tweaks (e.g., added braces around single-line if statements).

Security Hotspots

1. Refactor Scope & Dependency Management: While not directly a security risk, large-scale refactors can introduce bugs due to the vast number of dependencies and interactions within the system. Full regression testing should ensure no unintended side effects occur.

2. Feature Flag Consistency: Changes involve files related to feature flagging (features.cc, features.h). Ensuring these flags behave as expected post-refactor is crucial to maintaining intended functionality and security postures controlled by these flags.

3. Path Updates in Build Configs: Changes in the .gn files to reflect new paths ensure correct building and linking of components. Misconfiguration can lead to runtime errors, potentially exposing uninitialized or improperly secured resources.