Examine source code of NihongoTube

{
  "manifest_version": 2,
  "name": "__MSG_appName__",
  "description": "__MSG_appDescription__",
  "version": "6.2.0",
  "icons": {
    "16": "icon/16.png",
    "32": "icon/32.png",
    "48": "icon/48.png",
    "96": "icon/96.png",
    "128": "icon/128.png"
  },
  "default_locale": "en",
  "permissions": [
    "storage",
    "*://*.youtube.com/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "web_accessible_resources": [
    "icon_dark.svg",
    "icon_light.svg",
    "icon.svg",
    "icon_disabled.svg",
    "welcome.html",
    "settings.html",
    "stats.html",
    "playerapi-main-world.js"
  ],
  "browser_action": {
    "default_title": "NihongoTube",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "css": [
        "content-scripts/icon.css"
      ],
      "js": [
        "content-scripts/icon.js"
      ]
    },
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "run_at": "document_end",
      "css": [
        "content-scripts/react.css"
      ],
      "js": [
        "content-scripts/react.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{1c5849ce-dc73-4f2e-a899-a8a430618310}"
    }
  }
}