Examine source code of Yodel Phone System

{
  "name": "Yodel.io Business Phone System",
  "short_name": "Yodel",
  "version": "0.9.2resigned1",
  "description": "Click to call via yodel.io",
  "author": "YodelTalk",
  "homepage_url": "https://www.yodel.io",
  "manifest_version": 2,
  "icons": {
    "32": "icons/yodel-32.png",
    "48": "icons/yodel-48.png",
    "96": "icons/yodel-96.png",
    "128": "icons/yodel-128.png"
  },
  "browser_action": {
    "default_icon": {
      "19": "icons/toolbar.png",
      "38": "icons/toolbar@2x.png"
    },
    "default_popup": "options.html"
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": false
  },
  "permissions": [
    "storage",
    "tabs",
    "contextMenus"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "js": [
        "content_script.js"
      ],
      "run_at": "document_end",
      "all_frames": true
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{f50053ba-bcc5-4187-ae9b-762aba2e93f1}"
    }
  }
}