Examine source code of Wikipedia+

{
  "name": "Wikipedia+",
  "short_name": "wikipedia-plus",
  "description": "Add multiple features to wikipedia.org",
  "version": "1.1.7",
  "manifest_version": 2,
  "icons": {
    "512": "assets/wikipedia-plus-icon.png"
  },
  "browser_action": {
    "default_title": "Wikipedia+",
    "default_icon": {
      "512": "assets/wikipedia-plus-icon.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.wikipedia.org/*"
      ],
      "js": [
        "scripts/content.js"
      ],
      "run_at": "document_start",
      "all_frames": false
    }
  ],
  "background": {
    "scripts": [
      "scripts/background.js"
    ]
  }
}