Examine source code of YouTube AMOLED

{
  "manifest_version": 2,
  "name": "YouTube AMOLED",
  "version": "1.0",
  "description": "Changes YouTube's background to true black (#000000). Useful for saving battery on OLED screens.",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "permissions": [
    "activeTab",
    "*://*.youtube.com/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "css": [
        "styles.css"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "youtube-amoled-dark@example.com",
      "strict_min_version": "58.0"
    }
  }
}