Examine source code of MetricBlocker

{
  "manifest_version": 2,
  "name": "MetricBlocker",
  "version": "0.2resigned1",
  "author": "Rinat",
  "homepage_url": "https://hellosite.org",
  "description": "Блокирует Яндекс метрику, также Google Analytics и трекинг от mail.ru",
  "icons": {
    "48": "icons/main.png"
  },
  "applications": {
    "gecko": {
      "id": "MetricBlocker@hellosite.org",
      "strict_min_version": "45.0"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "webRequest",
    "<all_urls>",
    "webRequestBlocking"
  ]
}