Create ad blocking module with basic support for RC flags

[CrisBarreiro]

Task/Issue URL: https://app.asana.com/1/137249556945/project/72649045549333/task/1214489465023870?focus=true

Description

Add module and RC support for ad blocking

Steps to test this PR

n/a

UI changes

n/a

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Note

Low Risk
Low risk: this PR only scaffolds a new module and defines remote feature flags/data models, with no runtime wiring or behavior changes shown beyond adding new buildable sources.

Overview
Adds a new ad-blocking-impl Android library module wired for DI (anvil/ksp) and depends on feature-toggles-api/browser-api.

Introduces AdBlockingExtensionFeature as a @ContributesRemoteFeature with two RC-backed toggles (self and enabledByDefault, both defaulting to false) plus simple settings models (AdBlockingExtensionSettings, ScriptletEntry).

Adds a minimal ad-blocking/readme.md describing the feature and linking to design docs.

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[CrisBarreiro]

• Create ad blocking module with basic support for RC flags #8495 👈 (View in Graphite)
• develop

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[cmonfortep]

LGTM

NIT: if api is empty, we don't need to create it. We can just have -impl for now.

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[cursor]

Toggle named enabledByDefault defaults to FALSE

Medium Severity

The enabledByDefault() toggle is annotated with DefaultFeatureValue.FALSE, which contradicts its name. The codebase's own test fixture in FeatureTogglesTest establishes the convention that enabledByDefault() maps to DefaultFeatureValue.TRUE and disableByDefault() maps to DefaultFeatureValue.FALSE. If the intent is for this sub-feature to be off until RC enables it, the name is misleading and will confuse future readers; if the intent matches the name, the default value is wrong.

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