Examine source code of Cling Button

{
  "manifest_version": 2,
  "version": "5.0.7",
  "name": "__MSG_name__",
  "description": "__MSG_description__",
  "default_locale": "en",
  "permissions": [
    "storage",
    "activeTab",
    "scripting",
    "contextMenus"
  ],
  "optional_permissions": [
    "tabs"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://cling.com/*"
      ],
      "js": [
        "cling_content_script.js"
      ],
      "run_at": "document_start"
    }
  ],
  "background": {
    "scripts": [
      "service_worker.js"
    ]
  },
  "icons": {
    "128": "icons/icon_128.png",
    "192": "icons/icon_192.png",
    "256": "icons/icon_256.png",
    "512": "icons/icon_512.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{799cae34-c122-42e7-bdf3-bfaec217ccfb}"
    }
  },
  "browser_action": {
    "default_title": "__MSG_name__",
    "default_popup": "popup.html"
  }
}