Examine source code of Kalliope Caller

{
  "manifest_version": 2,
  "name": "Kalliope Caller",
  "description": "Chiamate dirette dal browser",
  "version": "1.0.3",
  "optional_permissions": [],
  "permissions": [
    "storage",
    "contextMenus",
    "notifications",
    "<all_urls>"
  ],
  "options_ui": {
    "page": "options/ui.html"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "icons": {
    "16": "assets/icons/icon_16.png",
    "32": "assets/icons/icon_32.png",
    "48": "assets/icons/icon_48.png",
    "128": "assets/icons/icon_128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "kalliopecaller@teknonet.it"
    }
  }
}