Examine source code of JustDeleteMe

{
  "manifest_version": 2,
  "name": "JustDeleteMe",
  "version": "1.7.0",
  "icons": {
    "128": "res/ext_icon_144.png"
  },
  "browser_action": {
    "default_icon": {
      "144": "res/ext_icon_144.png"
    },
    "default_popup": "pub/index.html"
  },
  "permissions": [
    "activeTab",
    "<all_urls>",
    "webNavigation"
  ],
  "background": {
    "scripts": [
      "js/background.js"
    ],
    "persistent": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{6f54ad3f-042f-408f-8f06-ab631fe1a64f}"
    }
  }
}