ViewController.swift

import UIKit
import WebKit

class ViewController: UIViewController {

    private var webview: WKWebView!
    private var controller: WebController = WebController()

    override func viewDidLoad() {
        super.viewDidLoad()

        let configuration = WKWebViewConfiguration()
        configuration.allowsInlineMediaPlayback = false
        configuration.mediaTypesRequiringUserActionForPlayback = []
        configuration.applicationNameForUserAgent = "Version/13.0.1 Safari/605.1.15"
        configuration.userContentController.addScriptMessageHandler(controller, contentWorld: WKContentWorld.page, name: "controller")
        webview = WKWebView(frame: view.bounds, configuration: configuration)
        webview.translatesAutoresizingMaskIntoConstraints = false

        view.addSubview(webview)

        webview.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
        webview.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
        webview.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
        webview.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
        webview.navigationDelegate = self
        webview.load(URLRequest(url: URL(string: "http://accounts.google.com/")!))

        //webview.load(URLRequest(url: URL(string: "https://gamepad-tester.com")!))
    }

    @objc private func goToStadia()
    {
        webview.customUserAgent = "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.83 Safari/537.36"
        webview.load(URLRequest(url: URL(string: "https://stadia.google.com")!))
    }

}

extension ViewController: WKNavigationDelegate {

    func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {

        if webview.url?.absoluteString == "https://stadia.google.com/home"
        {
            controller.setup(webview: webview)

        }
    }

    func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {

        if let url = navigationAction.request.url?.absoluteString
        {
            if url == "https://myaccount.google.com/"
            {
                decisionHandler(.cancel)
                goToStadia()
                return
            }
        }

        decisionHandler(.allow)
    }
}