[ads] RichNTT: Android

[aseren]

The PR introduces NewTabTakeover WebUI which does the following:

• retrieves sponsored wallpaper information via mojom
• displays rich media using <SponsoredRichMediaBackground> react component
• sends events from rich media NTT via mojom channel
• has an url: chrome://new-tab-takeover

NewTabTakeover webUI is loaded on Android NTP using ThinWebView wrapped inside FrameLayout.

Currently NewTabTakeover web ui is used on Android only, because Desktop implementation uses New Tab Page Web UI and doesn't need additional WebUI.

Security review: https://github.com/brave/reviews/issues/1795
Desktop implementation was done in: #27466

Resolves brave/brave-browser#43513

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:

Test the functionality basing on RichNTT spec: https://docs.google.com/document/d/14kFstJbrsYZyFmZcTAQac195riiinQoVAU1Dzk1e2dE/edit?tab=t.0#heading=h.skhkv2wammbc

[github-actions]

Chromium major version is behind target branch (133.0.6943.54 vs 134.0.6998.15). Please rebase.

[tmancey]

Approved (see comments). Thanks

[tmancey]

@bridiver on desktop, we use a Web UI to display new tab pages. On Android, however, there is no Web UI implementation. Instead, Android overlays a native view over a web contents view.

The native view displays the background image, Brave Stats, and Brave News. When the user navigates to a URL, the native view is hidden, revealing the web contents view and its HTML content.

To display rich media HTML alongside Brave Stats and Brave News, we use a ThinWebView to render the HTML behind these overlays.

cc @SergeyZhukovsky @deeppandya @aseren

[bridiver]

this is under brave_new_tab_ui in components, but not in browser https://github.com/brave/brave-core/pull/27645/files#diff-f72ebad5725bed17e104d5245827d8d7cfdee3b6b9f1c7f122af3555e6ddd48c

[aseren]

moved to components/new_tab_takeover directory

[bridiver]

Code owner ok

[github-actions]

[puLL-Merge] - brave/brave-core@27645

Here's my review of the PR:

Description

This PR adds support for rich media wallpapers in Brave's New Tab Page on Android. It introduces a new WebUI component called "New Tab Takeover" that can display HTML content behind the standard New Tab Page overlays (Brave Stats and Brave News). The motivation is to enable more interactive sponsored content in the wallpaper area.

Security Hotspots

1. Untrusted Content: The rich media content loads in an untrusted context (chrome-untrusted://), but care should be taken to ensure proper sandboxing and CSP restrictions are in place.

2. Touch Event Pass-through: The PR routes touch events to the rich media WebView when the user taps outside recycler view items. This could potentially allow unintended interactions if not properly bounded.

Changes

Changes

By filename:

android/brave_java_sources.gni:

• Added new SponsoredRichMediaWebView.java source

BraveNewTabPageLayout.java:

• Added rich media WebView support
• Added touch event handling for rich media content
• Added background frame layout for rich media

SponsoredRichMediaWebView.java:

• New class to handle rich media WebView initialization and loading

new_tab_takeover/ (new directory):

• New WebUI implementation for rich media content
• React components for rendering rich media
• Mojo interfaces for communication between Java and WebUI

ntp_background_images/:

• Added rich media wallpaper type support
• Added tests for wallpaper parsing
• Updated CSP to allow framing from new WebUI

The key flow is that when a rich media wallpaper is detected, a WebView is initialized to load and display the content, while maintaining the standard NTP UI overlays.```mermaid
sequenceDiagram
BraveNewTabPageLayout->>+SponsoredRichMediaWebView: initialize()
SponsoredRichMediaWebView->>+WebContents: create()
WebContents-->>-SponsoredRichMediaWebView: web_contents
SponsoredRichMediaWebView->>+ThinWebView: create()
ThinWebView-->>-SponsoredRichMediaWebView: web_view
SponsoredRichMediaWebView->>WebContents: loadUrl(chrome://new-tab-takeover)
NewTabTakeoverUI->>NewTabTakeoverMojom: getCurrentWallpaper()
NewTabTakeoverMojom-->>NewTabTakeoverUI: wallpaper info
NewTabTakeoverUI->>SponsoredRichMediaWebView: render rich media content

</details>

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[brave-builds]

Released in v1.78.4