Examine source code of Lyrics for YouTube

{
  "manifest_version": 2,
  "name": "Lyrics for YouTube",
  "description": "Veja letras de suas músicas favoritas",
  "version": "2.6.0",
  "author": "Hermanyo H. A. Souza",
  "icons": {
    "128": "icons/icon.png"
  },
  "content_scripts": [
    {
      "all_frames": true,
      "matches": [
        "*://*.youtube.com/*"
      ],
      "js": [
        "content_script.js"
      ],
      "css": [
        "style.css"
      ],
      "run_at": "document_start"
    }
  ],
  "content_security_policy": "default-src 'self' ; connect-src http://*",
  "browser_action": {
    "default_icon": {
      "96": "icons/logo.png"
    }
  },
  "background": {
    "persistent": true,
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "tabs",
    "<all_urls>",
    "webNavigation",
    "activeTab",
    "webRequest",
    "webRequestBlocking"
  ],
  "web_accessible_resources": [
    "icons/*"
  ]
}