Examine source code of PHP Revival

{
  "manifest_version": 2,
  "name": "PHP Revival",
  "version": "2.13.4",
  "web_accessible_resources": [
    "images/*"
  ],
  "description": "Extension that every PHP developer must have. Changes styles to php.net for a better experience of using documentation",
  "icons": {
    "32": "images/icon-32.png",
    "48": "images/icon-48.png",
    "64": "images/icon-64.png",
    "128": "images/icon-128.png"
  },
  "browser_action": {
    "default_icon": "images/icon-48.png",
    "default_title": "PHP revival"
  },
  "content_scripts": [
    {
      "matches": [
        "*://www.php.net/*",
        "*://php.net/*"
      ],
      "css": [
        "main.css"
      ],
      "run_at": "document_start"
    },
    {
      "matches": [
        "*://www.php.net/*",
        "*://php.net/*"
      ],
      "js": [
        "main.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{d042d87e-844f-4b3f-b693-64ce1849c8d0}"
    }
  }
}