Examine source code of Keyboard Navigator

{
  "manifest_version": 2,
  "name": "Navigator",
  "version": "3.0.0",
  "description": "Alt-layer keyboard navigation for the modern web",
  "permissions": [
    "storage",
    "tabs"
  ],
  "browser_action": {
    "default_icon": {
      "16": "assets/icons/icon16.png",
      "32": "assets/icons/icon32.png",
      "48": "assets/icons/icon48.png"
    },
    "default_title": "Navigator"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "commands": {},
  "icons": {
    "16": "assets/icons/icon16.png",
    "32": "assets/icons/icon32.png",
    "48": "assets/icons/icon48.png",
    "128": "assets/icons/icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "navigator@adyung",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}