Examine source code of Work Mode

{
  "manifest_version": 2,
  "name": "Work Mode",
  "version": "1.0",
  "description": "Block distracting websites in work mode",
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "<all_urls>",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_popup": "options.html"
  },
  "options_ui": {
    "page": "options.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{d4807e4b-d422-49f5-b570-f8d07ea1e3d4}"
    }
  }
}