Examine source code of TSE click2call

{
  "manifest_version": 2,
  "name": "Asterisk Click2Dial",
  "version": "1.0",
  "description": "This is an easy to use extension, call by clicking on the underlined number.",
  "author": "Ahmed Ezzar, Emilie Sinno, Ilyes Najjari, Lilian Chaptal",
  "icons": {
    "48": "icons/asterisk-48.png"
  },
  "permissions": [
    "storage",
    "menus",
    "webNavigation",
    "<all_urls>",
    "activeTab",
    "tabs"
  ],
  "browser_action": {
    "default_icon": {
      "20": "icons/asterisk-20.png",
      "32": "icons/asterisk-32.png"
    },
    "default_title": "Asterisk Click2Dial",
    "default_popup": "popup/popupAsterisk.html"
  },
  "options_ui": {
    "page": "options.html"
  },
  "background": {
    "scripts": [
      "asterisk.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "jquery-3.2.1.min.js",
        "content-script.js"
      ],
      "all_frames": true
    }
  ],
  "web_accessible_resources": [
    "content-script.js"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{d5bfe1e1-d273-488a-98b6-e3dc6c62b96e}"
    }
  }
}