Examine source code of axes

{
  "manifest_version": 2,
  "name": "axes",
  "version": "0.0.5resigned1",
  "description": "Makes the Web keyboard-accessible.",
  "icons": {
    "128": "img/icon.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "dist/content.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "dist/background.js"
    ]
  },
  "options_ui": {
    "page": "settings.html",
    "browser_style": true,
    "open_in_tab": true
  },
  "browser_action": {
    "default_icon": {
      "128": "img/button.png"
    },
    "default_title": "axes: open settings"
  },
  "permissions": [
    "storage",
    "tabs",
    "<all_urls>",
    "clipboardWrite",
    "downloads"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{ad97def7-9b36-4990-925d-3f570b910c8c}"
    }
  }
}