ScratchExt

manifest.json

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "name": "ScratchExt",
  "version": "1.2",
  "description": "Adds a button to the Scratch website that installs ScratchExt.",
  "icons": {
    "128": "logo.png"
  },
  "content_scripts": [
    {
      "matches": [
        "http://scratch.mit.edu/*"
      ],
      "js": [
        "script.js"
      ],
      "run_at": "document_end"
    }
  ],
  "permissions": [
    "tabs",
    "http://scratch.mit.edu/*"
  ],
  "manifest_version": 2,
  "content_security_policy": "default-src 'none'; style-src 'self'; script-src 'self'; connect-src http://scratch.mit.edu; img-src http://scratch.mit.edu"
}