Critical

manifest.json

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "name": "Critical",
  "version": "1.0.1",
  "description": "Extend the roll20 application",
  "manifest_version": 2,
  "permissions": [
    "declarativeContent",
    "activeTab"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "page_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "images/icon_16.png",
      "32": "images/icon_32.png",
      "48": "images/icon_48.png",
      "128": "images/icon_128.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "https://app.roll20.net/editor/"
      ],
      "css": [
        "extend.css"
      ],
      "js": [
        "extend.js"
      ],
      "run_at": "document_end"
    }
  ]
}