Examine source code of Wakatime client

{
  "manifest_version": 2,
  "name": "Wakatime client",
  "version": "2.0.0",
  "description": "Wakatime client",
  "icons": {
    "32": "icons/wakatime.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "wakatimeclient@nobad.coffee"
    }
  },
  "browser_action": {
    "default_icon": "icons/wakatime.png",
    "default_title": "Wakatime api",
    "default_popup": "popup/menu.html",
    "browser_style": true
  },
  "background": {
    "scripts": [
      "background_scripts/index.js"
    ]
  },
  "permissions": [
    "webRequest",
    "activeTab",
    "idle",
    "tabs",
    "<all_urls>",
    "storage"
  ]
}