Examine source code of Week Number

{
  "manifest_version": 2,
  "name": "__MSG_extName__",
  "description": "__MSG_extDescription__",
  "default_locale": "en",
  "version": "1.0",
  "browser_action": {
    "default_title": "__MSG_extName__",
    "default_popup": "popup.html"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "storage",
    "alarms"
  ],
  "icons": {
    "16": "public/icons/icon-16.png",
    "32": "public/icons/icon-32.png",
    "48": "public/icons/icon-48.png",
    "128": "public/icons/icon-128.png",
    "256": "public/icons/icon-256.png",
    "512": "public/icons/icon-512.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{994631ca-d89f-4263-8578-2d3a7c98ff43}"
    }
  }
}