Examine source code of Time Tracker for Articles

{
  "manifest_version": 2,
  "name": "Time Tracker for Articles",
  "version": "1.0",
  "description": "Calculates and displays estimated reading time for online articles, tracking total reading time per day or week.",
  "permissions": [
    "storage",
    "tabs",
    "activeTab"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icons/icon48.png"
  },
  "icons": {
    "48": "icons/icon48.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{6ee9e2d4-61a1-4214-b827-84fe85f14ef6}"
    }
  }
}