[iOS] Move web view delegate logic into a shared components

[kylehickinson]

This change moves a majority of logic that used to live in BVC+WKNavigationDelegate.swift into 3 separate protocols:

• TabWebDelegate: Defines methods that match up with WKUIDelegate/WKNavigationDelegate methods, but will be expanded on to be methods that can only be handled by one implementer.
• TabWebNavigationDelegate: Defines methods that match up with WKNavigationDelegate navigational movement methods, will eventually become TabWebObserver in the future and allow multiple observers
• TabWebPolicyDecider: Defines the policy deciders of the WKNavigationDelegate

The biggest change is that these Tab prefixed methods simply pass in a Tab and no longer have access to the underlying WKWebView directly from the delegate method, this is to ensure we split out the WebKit-specific logic that will be only run when using WKWebView directly vs using Chromium web views via CWVWebView

Resolves brave/brave-browser#44126

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:

Re-verify/Sanity test:

• Web browsing in general
• JS alerts/prompts + prompt suppression
• Basic auth navigation
• Media device permission prompts (microphone, camera)
• Downloads
• Playlist streaming/offline downloads

[kylehickinson]

These tests were already disabled for a long time

[github-actions]

The security team is monitoring all repositories for certain keywords. This PR includes the word(s) "policy" and so security team members have been added as reviewers to take a look.

No need to request a full security review at this stage, the security team will take a look shortly and either clear the label or request more information/changes.

Notifications have already been sent, but if this is blocking your merge feel free to reach out directly to the security team on Slack so that we can expedite this check.

[github-actions]

[puLL-Merge] - brave/brave-core@27746

Description

This PR reorganizes web navigation and policy decisions in the iOS app to decouple the logic into more manageable components. The key changes include introducing protocol-based interfaces for web navigation, web policies, and user interactions. The changes also improve security by better isolating privileged calls and implementing safer protocols.

Changes

Changes

1. BraveSkusAccountLink.swift:

• Changed injectLocalStorage to take a Tab parameter instead of WKWebView

2. BrowserPrompts.swift:

• Changed frame parameter to origin in alert info structs
• Removed legacy host title generation code
• Refactored to use URL origin directly for titles

3. New Files Added:

• BVC+TabWebDelegate.swift: Handles user interaction with web content
• BVC+TabWebNavigationDelegate.swift: Manages web navigation events
• BVC+TabWebPolicyDecider.swift: Makes web policy decisions
• UniversalLinkNavigationHelper.swift: Handles universal link navigation

4. Files Removed:

• TabManagerNavDelegate.swift: Functionality moved into new protocol-based components
• TabSessionTests.swift: Tests split and moved into new test files

5. BrowserViewController:

• Refactored to use new protocol-based components
• Improved tab, navigation and web view lifecycle management

sequenceDiagram
    participant User
    participant BVC as BrowserViewController
    participant TabWebDelegate
    participant TabWebNavigationDelegate 
    participant TabWebPolicyDecider
    participant WKWebView

    User->>BVC: Interacts with WebView
    BVC->>TabWebDelegate: Handles User Interactions
    BVC->>TabWebNavigationDelegate: Manages Navigation
    TabWebNavigationDelegate->>TabWebPolicyDecider: Makes Policy Decisions
    TabWebPolicyDecider->>WKWebView: Applies Navigation Policy
    WKWebView-->>BVC: Navigation Result

Loading

Security Hotspots

1. Sensitive Data Exposure: Care should be taken when handling URL redirects and origin data, particularly in TabWebDelegate where origin information is exposed in alerts.

2. Universal Link Handling: The new universal link navigation helper exposes sensitive domains - ensure lists are up-to-date and handling is secure.

Possible Issues

1. Browser State Changes: The page zoom state reset functionality has changed and needs thorough testing during navigation.

2. Memory Management: Many closures were restructured - memory management and lifecycle timing need validation.

[StephenHeaps]

nit: can we prefix these with brave-ios while we are moving them (and below in same comment)? Ex. brave-ios#3323

[kylehickinson]

Will address in the next PR 🙂

[brave-builds]

Released in v1.78.4

[StephenHeaps]

If uplifted please uplift #27891