Examine source code of Tab Badge

{
  "manifest_version": 2,
  "name": "Tab Badge",
  "description": "Shows a small badge with the unread count (the number between parentheses in the page's title) of the tabs over their favicon.",
  "version": "1.0.2resigned1",
  "browser_specific_settings": {
    "gecko": {
      "id": "tabbadge@sarics"
    }
  },
  "icons": {
    "16": "icons/icon.svg",
    "32": "icons/icon.svg",
    "48": "icons/icon.svg",
    "64": "icons/icon.svg",
    "96": "icons/icon.svg"
  },
  "permissions": [
    "http://*/*",
    "https://*/*",
    "storage",
    "tabs"
  ],
  "background": {
    "scripts": [
      "background/background.js"
    ]
  },
  "options_ui": {
    "page": "options/options.html",
    "browser_style": false,
    "open_in_tab": true
  }
}