Examine source code of Worldwide Radio

{
  "manifest_version": 2,
  "name": "__MSG_extension_name__",
  "short_name": "__MSG_extension_name__",
  "description": "__MSG_extension_description__",
  "author": "Oleksandr Popov",
  "version": "5.2",
  "default_locale": "en",
  "applications": {
    "gecko": {
      "id": "worldwide@radio"
    }
  },
  "icons": {
    "16": "/skin/logo16.png",
    "24": "/skin/logo24.png",
    "32": "/skin/logo32.png",
    "48": "/skin/logo48.png",
    "128": "/skin/logo128.png"
  },
  "browser_action": {
    "default_icon": "/skin/logo24.png",
    "default_popup": "content/popup.html",
    "default_title": "__MSG_extension_name__"
  },
  "background": {
    "page": "content/background.html"
  },
  "options_ui": {
    "page": "content/options.html",
    "chrome_style": false,
    "open_in_tab": true
  },
  "optional_permissions": [
    "downloads"
  ],
  "content_security_policy": "script-src 'self' blob:; object-src 'self'",
  "permissions": [
    "storage",
    "unlimitedStorage",
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ]
}