Examine source code of Telsome Click2Call

{
  "manifest_version": 2,
  "name": "Telsome Click2Call",
  "version": "1.8resigned1",
  "description": "Convierte cualquier número de teléfono en un enlace para llamar desde tu extensión de Telsome.",
  "homepage_url": "https://www.telsome.es",
  "icons": {
    "48": "icons/click2call-48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "jquery-3.2.1.min.js",
        "click2call.js"
      ]
    }
  ],
  "applications": {
    "gecko": {
      "id": "click2call_ff@telsome.es"
    }
  },
  "options_ui": {
    "page": "options.html"
  },
  "background": {
    "scripts": [
      "jquery-3.2.1.min.js",
      "context_menu.js"
    ]
  },
  "permissions": [
    "*://*.telsome.es/*",
    "contextMenus",
    "webRequest",
    "activeTab",
    "storage",
    "notifications",
    "tabs"
  ],
  "browser_action": {
    "default_icon": "icons/click2call-32.png",
    "default_title": "Telsome Click2Call",
    "default_popup": "popup/configure.html"
  },
  "web_accessible_resources": [
    "img/telsome.png"
  ]
}