Examine source code of Broll Youtube Thumbnail

{
  "manifest_version": 2,
  "name": "__MSG_extensionName__",
  "description": "__MSG_extensionDescription__",
  "version": "0.4",
  "default_locale": "en",
  "author": "rztprog",
  "browser_specific_settings": {
    "gecko": {
      "strict_min_version": "56.0a1",
      "id": "{865955d4-a8c5-40dc-896b-3f339c555bea}"
    }
  },
  "permissions": [
    "activeTab",
    "contextMenus",
    "tabs",
    "storage",
    "downloads",
    "clipboardWrite",
    "https://broll.gabin.app/"
  ],
  "icons": {
    "48": "icons/broll48.png",
    "96": "icons/broll96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "js": [
        "./src/mouseEventMessage.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "./src/broll.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "48": "icons/broll48.png",
      "96": "icons/broll96.png"
    },
    "default_title": "Broll Youtube Thumbnail",
    "default_popup": "./src/popup.html"
  }
}