Examine source code of Youtube Theme

{
  "manifest_version": 2,
  "name": "Youtube Theme",
  "short_name": "__MSG_description__",
  "description": "__MSG_description__",
  "default_locale": "en",
  "version": "1.0.4resigned1",
  "author": "Light Alex",
  "icons": {
    "48": "icons/48.png",
    "64": "icons/64.png",
    "128": "icons/128.png",
    "256": "icons/256.png"
  },
  "browser_action": {
    "default_icon": {
      "16": "icons/popup_dark_16.png",
      "24": "icons/popup_dark_24.png",
      "32": "icons/popup_dark_32.png"
    }
  },
  "background": {
    "scripts": [
      "files/scripts/background.js"
    ]
  },
  "permissions": [
    "tabs",
    "http://*/*",
    "https://*/*",
    "browsingData",
    "cookies",
    "storage",
    "webRequest",
    "webRequestBlocking"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://youtube.com/*",
        "*://www.youtube.com/*"
      ],
      "css": [
        "files/styles/main.css"
      ],
      "js": [
        "files/scripts/preload.js"
      ],
      "run_at": "document_start"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{c0acd3ac-e26f-4974-ad65-66f5cf46bcf7}"
    }
  }
}