Examine source code of Color Mood Extractor

{
  "manifest_version": 2,
  "name": "Color Mood Extractor",
  "version": "1.0.0",
  "description": "Show dominant color palette (3-5 colors) when hovering over images.",
  "icons": {
    "48": "icons/icon48.png",
    "96": "icons/icon96.png",
    "128": "icons/icon128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content_script.js"
      ],
      "css": [
        "styles.css"
      ],
      "run_at": "document_idle"
    }
  ],
  "permissions": [],
  "browser_specific_settings": {
    "gecko": {
      "id": "colormood@example.com",
      "strict_min_version": "91.0"
    }
  }
}