Examine source code of Reddit Portal

{
  "manifest_version": 2,
  "name": "Reddit Portal",
  "version": "1.0",
  "description": "A simple shortcut to Reddit communities by typing \"r/\" in the browser URL",
  "icons": {
    "48": "icons/48.png"
  },
  "permissions": [
    "activeTab"
  ],
  "background": {
    "scripts": [
      "main.js"
    ]
  },
  "omnibox": {
    "keyword": "r/"
  }
}