Examine source code of Safe Facebook

{
  "manifest_version": 2,
  "name": "Safe Facebook",
  "version": "1.0.0",
  "description": "Protect you from tracking by Facebook. Now you can use Facebook, Instagram, Messenger etc without any troubles",
  "icons": {
    "48": "icon.png",
    "96": "icon@2x.png"
  },
  "applications": {
    "gecko": {
      "id": "@safe-facebook",
      "strict_min_version": "57.0"
    }
  },
  "homepage_url": "https://github.com/mozilla/contain-facebook",
  "permissions": [
    "<all_urls>",
    "contextualIdentities",
    "cookies",
    "management",
    "tabs",
    "webRequestBlocking",
    "webRequest"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  }
}