chrome.webRequest.onBeforeRequest.addListener(function (details) {
  return { redirectUrl: 'https://bar.com'};
}, {urls: ['https://foo.com/']}, ['blocking']);

{
  "name": "redirect",
  "description": "Redirect foo to bar.",
  "version": "1.0",
  "permissions": ["webRequest", "webRequestBlocking", "https://foo.com/"],
  "background": { "scripts": ["background.js"] },
  "manifest_version": 2
}