Examine source code of Async CSS

{
  "name": "__MSG_extensionName__",
  "author": "Terry",
  "version": "0.2.6",
  "description": "__MSG_extensionDescription__",
  "manifest_version": 2,
  "default_locale": "en",
  "icons": {
    "16": "icon_16.png",
    "20": "icon_20.png",
    "24": "icon_24.png",
    "38": "icon_38.png",
    "48": "icon_48.png",
    "96": "icon_96.png"
  },
  "permissions": [
    "<all_urls>",
    "webRequest",
    "webRequestBlocking",
    "storage"
  ],
  "applications": {
    "gecko": {
      "strict_min_version": "57.0"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "browser_action": {
    "default_icon": {
      "16": "iconoff_16.png",
      "20": "iconoff_20.png",
      "24": "iconoff_24.png",
      "38": "iconoff_38.png",
      "48": "iconoff_48.png"
    }
  },
  "options_ui": {
    "chrome_style": true,
    "page": "options.html"
  }
}