Examine source code of Hover Chase

{
  "manifest_version": 2,
  "name": "Hover Chase",
  "version": "1.0",
  "description": "Some elements run away when hovered. Catch them with the mouse to score points.",
  "icons": {
    "48": "icon48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content_script.js"
      ],
      "run_at": "document_end"
    }
  ],
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{f4026d81-06fa-4be5-8a67-3a3c634bd43b}"
    }
  }
}