Examine source code of Easy Auto Refresh

{
  "name": "Easy Auto Refresh",
  "version": "5.6",
  "manifest_version": 2,
  "description": "Auto-refresh and auto-reload pages after any number of seconds.",
  "background": {
    "page": "background.html"
  },
  "page_action": {
    "default_icon": {
      "38": "images/refresh-off-38.png"
    },
    "default_title": "Easy Auto Refresh",
    "default_popup": "popup.html"
  },
  "permissions": [
    "tabs",
    "browsingData",
    "notifications",
    "http://*/",
    "https://*/"
  ],
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "js": [
        "scripts/keypress.js"
      ],
      "run_at": "document_start"
    }
  ],
  "icons": {
    "48": "images/easy-auto-refresh-48x48.png",
    "128": "images/easy-auto-refresh-128x128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{ea46d81a-e73f-4846-839f-5c04a891dc97}"
    }
  }
}