Examine source code of Amazon Enhancer

{
  "manifest_version": 2,
  "name": "Amazon Enhancer",
  "version": "0.3resigned1",
  "description": "Enhances Amazon shopping experience!",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "applications": {
    "gecko": {
      "id": "AmazonEnhancer@protonmail.com"
    }
  },
  "browser_action": {
    "default_icon": "icons/icon-32.png",
    "default_title": "Amazon Enhancer",
    "default_popup": "html/options.html"
  },
  "web_accessible_resources": [
    "css/clean.css",
    "css/dark.css"
  ],
  "options_ui": {
    "page": "html/options.html",
    "browser_style": true
  },
  "permissions": [
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*.amazon.com/*"
      ],
      "js": [
        "js/enhancer.js"
      ],
      "run_at": "document_start",
      "all_frames": true
    }
  ]
}