Examine source code of 8x8 Web Dialer

{
  "manifest_version": 3,
  "name": "8x8 Web Dialer",
  "version": "2.9.0",
  "description": "Call any phone number straight from where you are on a web page.",
  "icons": {
    "16": "assets/images/icon16.png",
    "48": "assets/images/icon48.png",
    "128": "assets/images/icon128.png"
  },
  "action": {
    "default_area": "navbar"
  },
  "background": {
    "scripts": [
      "scripts/background.js"
    ],
    "type": "module"
  },
  "options_ui": {
    "page": "scripts/options/options.html",
    "open_in_tab": false
  },
  "permissions": [
    "contextMenus",
    "webNavigation",
    "storage",
    "tabs",
    "activeTab"
  ],
  "host_permissions": [
    "<all_urls>",
    "https://*.8x8.com/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "scripts/main.js"
      ],
      "css": [
        "scripts/main.css"
      ],
      "all_frames": false
    }
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "/assets/svgs/phone.svg",
        "/assets/svgs/message.svg",
        "/assets/svgs/tinyLogo.svg"
      ],
      "matches": [
        "<all_urls>"
      ]
    }
  ],
  "content_security_policy": {
    "extension_pages": "script-src 'self'; object-src 'self'"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "click2call@8x8.com"
    }
  }
}