Examine source code of focus mode

{
  "manifest_version": 2,
  "name": "Focus Mode",
  "version": "1.0",
  "description": "Block distracting websites and help you focus",
  "permissions": [
    "storage",
    "webRequest",
    "webRequestBlocking",
    "tabs",
    "history",
    "notifications",
    "<all_urls>"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start"
    }
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icon.png"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "web_accessible_resources": [
    "blocked.html"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{32bf7b5d-1e34-453a-baa5-f4eadcdaa727}"
    }
  }
}