Extend webview testcases with MSTG-Platform-10

[commjoen]

MSTG-Platform-10: A WebView's cache, storage, and loaded resources (JavaScript, etc.) should be cleared before the WebView is destroyed.

• Android MSTG-PLATFORM-10 Add WebViews Cleanup #1984
• iOS TBD

Maybe include to do the cleanup when a webview has hung? https://developer.android.com/about/versions/10/features#webview-hung

Research notes for iOS

Check WebView Config / init for params/functions preventing files from being stored in the first place

One option is to use WKWebsiteDataStore.nonPersistent(). Example here:

https://github.com/duckduckgo/iOS/blob/cb600c312c1c9884f72d0cffe00318dd0de9faab/Core/WKWebViewConfigurationExtension.swift

This is old code but check if it's good for whenever nonPersistent is not an option:

// https://gist.github.com/insidegui/4a5de215a920885e0f36294d51263a15

    HTTPCookieStorage.shared.removeCookies(since: Date.distantPast)
WKWebsiteDataStore.default().fetchDataRecords(ofTypes: WKWebsiteDataStore.allWebsiteDataTypes()) { records in
    records.forEach { record in
        WKWebsiteDataStore.default().removeData(ofTypes: record.dataTypes, for: [record], completionHandler: {})
        print("Cookie ::: \(record) deleted")
    }
}

More useful linnks for the research:

• https://github.com/mozilla-mobile/focus-ios/blob/main/Blockzilla/WebCacheUtils.swift
• https://github.com/duckduckgo/iOS/blob/cb600c312c1c9884f72d0cffe00318dd0de9faab/Core/WebCacheManager.swift
• https://github.com/mozilla-mobile/firefox-ios/blob/main/Client/Frontend/Settings/Clearables.swift