Examine source code of Scratch Extension

{
  "manifest_version": 2,
  "name": "Scratch Extension",
  "version": "1.1.3",
  "description": "Multipurpose extension for scratch.mit.edu",
  "icons": {
    "32": "favicon.png"
  },
  "background": {
    "scripts": [
      "ScratchApi.js",
      "Debug.js",
      "background.js"
    ],
    "persistent": true
  },
  "browser_action": {
    "default_icon": "favicon.png",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "run_at": "document_start",
      "matches": [
        "https://scratch.mit.edu/*"
      ],
      "js": [
        "inject/inject.js"
      ]
    }
  ],
  "web_accessible_resources": [
    "inject/inject.css",
    "inject/dark theme/*.css",
    "inject/icons_xs.png"
  ],
  "permissions": [
    "alarms",
    "storage",
    "tabs",
    "cookies",
    "webRequest",
    "webRequestBlocking",
    "https://api.scratch.mit.edu/",
    "https://scratch.mit.edu/*"
  ],
  "applications": {
    "gecko": {
      "id": "scratchExtension@peabrainiac.blogspot.com"
    }
  }
}