Examine source code of Reading Time Estimators

{
  "manifest_version": 2,
  "name": "Reading Time Estimator",
  "version": "1.0",
  "description": "Estimates the reading time of the selected text on a webpage.",
  "permissions": [
    "activeTab"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_title": "Estimate Reading Time"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{09b3755c-35be-4b81-b762-60f0eeb1e0be}"
    }
  }
}