Examine source code of WakaTime

{
  "background": {
    "persistent": false,
    "scripts": [
      "public/js/browser-polyfill.min.js",
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "19": "graphics/wakatime-logo-19.png",
      "38": "graphics/wakatime-logo-38.png"
    },
    "default_popup": "popup.html",
    "default_title": "WakaTime"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "addons@wakatime.com",
      "strict_min_version": "58.0"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "wakatimeScript.js"
      ],
      "run_at": "document_end"
    }
  ],
  "description": "Automatic time tracking for Firefox.",
  "devtools_page": "devtools.html",
  "homepage_url": "https://wakatime.com",
  "icons": {
    "16": "graphics/wakatime-logo-16.png",
    "48": "graphics/wakatime-logo-48.png",
    "128": "graphics/wakatime-logo-128.png"
  },
  "manifest_version": 2,
  "name": "WakaTime",
  "options_ui": {
    "chrome_style": false,
    "page": "options.html"
  },
  "permissions": [
    "alarms",
    "tabs",
    "storage",
    "activeTab",
    "https://api.wakatime.com/*",
    "https://wakatime.com/*"
  ],
  "optional_permissions": [
    "<all_urls>"
  ],
  "version": "4.1.0"
}