Examine source code of Just Google It

{
  "name": "Just Google It",
  "description": "Didn't find what you need on your preferred search engine? You may need to just Google it.",
  "version": "1.0.2",
  "manifest_version": 2,
  "author": "Derek Czysz",
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icons/icon-32.png",
    "default_title": "Just Google It"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.qwant.com/*",
        "*://*.duckduckgo.com/*",
        "*://*.startpage.com/*",
        "*://*.searx.me/*",
        "*://*.bing.com/*",
        "*://*.yahoo.com/*"
      ],
      "js": [
        "contentScript.js"
      ],
      "run_at": "document_start"
    }
  ],
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Ctrl+Shift+F",
        "mac": "MacCtrl+Shift+F"
      },
      "description": "Opens popup.html"
    }
  },
  "permissions": [
    "*://*.google.com/*",
    "*://*.qwant.com/*",
    "*://*.duckduckgo.com/*",
    "*://*.startpage.com/*",
    "*://*.searx.me/*",
    "*://*.bing.com/*",
    "*://*.yahoo.com/*",
    "activeTab"
  ]
}