Works on my Machine! Badge Extension

manifest.json

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "name": "Works on my Machine! Badge Extension",
  "version": "1.0.2",
  "description": "This simple Chrome extension toggles a 'Works on my Machine!' badge on any web page.",
  "icons": {
    "16": "assets/images/icon16.png",
    "24": "assets/images/icon24.png",
    "32": "assets/images/icon32.png",
    "64": "assets/images/icon64.png",
    "128": "assets/images/icon128.png"
  },
  "browser_action": {
    "default_icon": {
      "16": "assets/images/icon16.png",
      "24": "assets/images/icon24.png",
      "32": "assets/images/icon32.png",
      "64": "assets/images/icon64.png",
      "128": "assets/images/icon128.png"
    },
    "default_title": "Works on my Machine!"
  },
  "background": {
    "scripts": [
      "src/background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "css": [
        "assets/styles/badge.css"
      ],
      "js": [
        "src/content.js"
      ]
    }
  ],
  "permissions": [
    "activeTab"
  ],
  "web_accessible_resources": [
    "assets/images/badge.png"
  ],
  "manifest_version": 2
}