Examine source code of 55PBX Webphone

{
  "manifest_version": 2,
  "name": "55PBX Webphone",
  "description": "Extensão de Webphone 55PBX (softphone web) para Google Chrome",
  "version": "1.3resigned1",
  "background": {
    "persistent": true,
    "scripts": [
      "popup.js"
    ]
  },
  "browser_action": {
    "default_icon": "/assets/55_logo_16.png"
  },
  "icons": {
    "16": "/assets/55_logo_16.png",
    "48": "/assets/55_logo_48.png",
    "128": "/assets/55_logo_128.png"
  },
  "permissions": [
    "notifications",
    "tabs",
    "activeTab",
    "https://ajax.googleapis.com/",
    "https://fone.55pbx.com/"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{d54d90f2-cea9-4edf-9fe2-85636ff3aa87}"
    }
  }
}