Examine source code of CallOne VoIP Softphone

{
  "name": "CallOne VoIP Softphone",
  "description": "__MSG_appDescription__",
  "homepage_url": "https://www.callone.de",
  "version": "1.5.7",
  "default_locale": "en",
  "manifest_version": 2,
  "permissions": [
    "notifications",
    "storage",
    "https://connect.callone.io/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*",
        "file://*/*"
      ],
      "all_frames": true,
      "run_at": "document_idle",
      "css": [
        "/css/content.css"
      ],
      "js": [
        "/javascript/helper.js",
        "/javascript/i18n.js",
        "/javascript/content.js"
      ]
    }
  ],
  "web_accessible_resources": [
    "images/logo_company.svg"
  ],
  "background": {
    "scripts": [
      "/javascript/3rd_party/sip-0.20.0.min.js",
      "/javascript/helper.js",
      "/javascript/i18n.js",
      "/javascript/voip.js",
      "/javascript/background.js"
    ],
    "persistent": true
  },
  "browser_action": {
    "default_title": "CallOne VoIP Softphone",
    "default_icon": "/images/icon_128px.png",
    "default_popup": "/html/popup.html"
  },
  "icons": {
    "16": "/images/icon_16px.png",
    "128": "/images/icon_128px.png"
  }
}