Examine source code of Tab Count in Window Title

{
  "manifest_version": 2,
  "name": "Tab Count in Window Title",
  "version": "5.7",
  "default_locale": "en",
  "applications": {
    "gecko": {
      "strict_min_version": "60.0",
      "id": "{c28e42b2-28b5-45f0-bdc8-6989ae7e6a7e}"
    }
  },
  "options_ui": {
    "page": "options/options.html"
  },
  "permissions": [
    "storage"
  ],
  "optional_permissions": [
    "tabs",
    "sessions"
  ],
  "background": {
    "page": "background/background.html"
  },
  "browser_action": {
    "default_icon": {
      "16": "icons/popup-16-light.png"
    },
    "default_popup": "popup/popup.html",
    "theme_icons": [
      {
        "light": "icons/popup-16-dark.png",
        "dark": "icons/popup-16-light.png",
        "size": 16
      }
    ],
    "browser_style": false
  },
  "commands": {
    "_execute_browser_action": {}
  }
}