Examine source code of Tabs Counter

{
  "description": "Stop counting with your fingers and toes. Tabs Counter came to rescue.",
  "manifest_version": 2,
  "name": "Tabs Counter",
  "version": "1.1",
  "icons": {
    "45": "icons/T.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "danielpro875@gmail.com"
    }
  },
  "background": {
    "scripts": [
      "TabsCounter.js"
    ]
  },
  "browser_action": {
    "default_icon": "icons/T.png"
  }
}