Examine source code of Responsively Helper

{
  "name": "Responsively Helper",
  "version": "0.0.2",
  "description": "An extension to open current browser page in Responsively app",
  "homepage_url": "https://responsively.app",
  "manifest_version": 2,
  "icons": {
    "16": "logo_16.png",
    "48": "logo_48.png",
    "128": "logo_128.png"
  },
  "background": {
    "persistent": false,
    "scripts": [
      "browser-polyfill.min.js",
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": "logo_128.png",
    "default_title": "Open page in Responsively app",
    "default_popup": "popup.html"
  },
  "permissions": [
    "activeTab"
  ]
}