Examine source code of TimeClip Clipper

{
  "manifest_version": 2,
  "name": "TimeClip Clipper",
  "description": "YouTubeを観ながら、その区間をTimeClipのクリップにできる拡張機能。",
  "version": "0.1.0",
  "icons": {
    "16": "icon/16.png",
    "32": "icon/32.png",
    "48": "icon/48.png",
    "96": "icon/96.png",
    "128": "icon/128.png"
  },
  "permissions": [
    "storage",
    "https://www.youtube.com/*",
    "https://timeclip.app/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "clipper@timeclip.app",
      "data_collection_permissions": {
        "required": [
          "authenticationInfo",
          "websiteContent"
        ]
      }
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "TimeClip Clipper",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.youtube.com/*"
      ],
      "run_at": "document_idle",
      "js": [
        "content-scripts/youtube.js"
      ]
    }
  ]
}