Examine source code of Development Icon Tab

{
  "manifest_version": 2,
  "name": "Development Icon Tab",
  "version": "1.0",
  "description": "Displays an icon before the tab title when you are browsing through a 'test' domain defined as localhost, 127.0.0.1, .dev, .test etc",
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "browser_action": {
    "default_icon": "icons/icon48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "include_globs": [
        "*developer*",
        "*dev*",
        "*staging*",
        "*test*",
        "*127.0.0.1*",
        "*localhost*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_end"
    }
  ],
  "web_accessible_resources": [
    "icons/*.png"
  ],
  "permissions": [
    "tabs",
    "activeTab",
    "storage"
  ]
}