Examine source code of Dev Mode

{
  "manifest_version": 2,
  "name": "Dev Mode",
  "version": "1.0.1",
  "description": "A simple helper extension for developers working on localhost environments.",
  "browser_specific_settings": {
    "gecko": {
      "id": "devmode@d7om.dev"
    }
  },
  "permissions": [
    "activeTab",
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://localhost/*",
        "*://127.0.0.1/*"
      ],
      "js": [
        "content.js",
        "utils.js"
      ],
      "css": [
        "styles.css"
      ],
      "run_at": "document_end"
    }
  ],
  "icons": {
    "48": "icon48.png",
    "96": "icon96.png",
    "128": "icon128.png"
  },
  "homepage_url": "https://github.com/d7omdev/devmode"
}