Examine source code of Confettify

{
  "manifest_version": 2,
  "name": "Confettify",
  "version": "0.1.1",
  "description": "Adds confetti to all assignments!",
  "icons": {
    "48": "icons/confettify-48x48.png",
    "64": "icons/confettify-64x64.png",
    "96": "icons/confettify-96x96.png",
    "128": "icons/confettify-128x128.png"
  },
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "storage",
    "https://*.instructure.com/*/assignments/*"
  ],
  "optional_permissions": [
    "<all_urls>"
  ],
  "options_ui": {
    "page": "options.html",
    "browser_style": true,
    "chrome_style": true
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{d39cc3ca-5a2b-4d1b-9074-e6bec9a27d05}"
    }
  }
}