Examine source code of RefCapturer

{
  "manifest_version": 2,
  "name": "RefCapturer",
  "version": "1.0",
  "description": "Save images to refern.app for art reference with a single click.",
  "permissions": [
    "activeTab"
  ],
  "icons": {
    "48": "icon.png"
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{740c7696-d2e5-4005-a8f4-ecf4daa739ed}"
    }
  }
}