Examine source code of Yet Another W3C Validator

{
  "author": "Andreas Rieber",
  "name": "Yet Another W3C Validator",
  "description": "YAW3CV: Validate HTML using local/remote W3C page validation service",
  "manifest_version": 2,
  "version": "2.0.5",
  "homepage_url": "https://bitbucket.org/arieber/yaw3cv/",
  "icons": {
    "48": "icons/yaW3Cv48.png",
    "96": "icons/yaW3Cv96.png"
  },
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "<all_urls>",
    "activeTab",
    "tabs",
    "storage",
    "notifications"
  ],
  "browser_action": {
    "default_icon": "icons/check-default.svg",
    "default_title": "W3C Validation",
    "default_popup": "popup/popup.html",
    "browser_style": true
  },
  "background": {
    "scripts": [
      "main/background.js",
      "main/validation.js"
    ]
  },
  "options_ui": {
    "page": "options/options.html",
    "browser_style": true
  },
  "applications": {
    "gecko": {
      "strict_min_version": "57.0a1"
    }
  }
}