Examine source code of ImageHighlighter

{
  "manifest_version": 2,
  "name": "ImageHighlighter",
  "version": "1.0",
  "description": "Draw or highlight directly on images within the browser, like annotating a PDF.",
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{269e6be5-988e-4a33-9efa-11fbdb6910ab}"
    }
  }
}