Examine source code of Reddit Account Age

{
  "manifest_version": 2,
  "name": "Reddit Account Age",
  "version": "0.3.0",
  "description": "Displays the age of reddit accounts next to their username",
  "content_scripts": [
    {
      "matches": [
        "*://*.reddit.com/*"
      ],
      "js": [
        "main.js"
      ]
    }
  ],
  "permissions": [
    "*://*.reddit.com/*",
    "storage"
  ],
  "options_ui": {
    "page": "options.html",
    "browser_style": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{6ef680e0-a61b-4769-8166-9d5d13e52646}"
    }
  }
}