Examine source code of Tempo Time Tracker

{
  "manifest_version": 2,
  "name": "Tempo Time Tracker",
  "description": "An extension that allows easily log time into the Tempo Jira plugin",
  "version": "0.0.18",
  "browser_action": {
    "default_icon": "assets/logo_16.png",
    "default_popup": "index.html"
  },
  "background": {
    "scripts": [
      "backgroundScript.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "https://app.tempo.io/*"
      ],
      "js": [
        "/contentScript.js"
      ],
      "all_frames": true
    }
  ],
  "icons": {
    "16": "assets/logo_16.png",
    "48": "assets/logo_48.png",
    "128": "assets/logo_128.png"
  },
  "permissions": [
    "storage",
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{240859e2-3776-46bf-b70c-4f8ed2c15ce3}"
    }
  }
}