Examine source code of Page Load Timer Plus

{
  "manifest_version": 2,
  "name": "Page Load Timer Plus",
  "version": "1.0",
  "description": "Measures page load time and provides additional useful features",
  "icons": {
    "48": "icon48.png",
    "96": "icon96.png"
  },
  "permissions": [
    "webNavigation",
    "storage",
    "tabs",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_icon": "icon48.png",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{e625ca7b-c35b-4d62-9873-c7af0896ef2e}"
    }
  }
}