Examine source code of Reading Time Estimator

{
  "manifest_version": 2,
  "name": "Reading Time Estimator",
  "version": "1.0",
  "description": "Estimate time required to read the page based on word count.",
  "browser_action": {
    "default_icon": {
      "64": "icon64.png",
      "128": "icon128.png"
    },
    "default_popup": "popup.html"
  },
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{4e146f1c-5112-484a-af1f-c4aee25cd595}",
      "strict_min_version": "116.0"
    }
  }
}