Examine source code of BitRef

{
  "manifest_version": 2,
  "name": "BitRef",
  "version": "1.2",
  "applications": {
    "gecko": {
      "id": "office@peername.com"
    }
  },
  "description": "Check Bitcoin Address Balance Tool",
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "background": {
    "scripts": [
      "bitref.js"
    ]
  },
  "omnibox": {
    "keyword": "btc"
  },
  "permissions": [
    "https://bitref.com/*"
  ],
  "homepage_url": "https://bitref.com/"
}