Examine source code of Big Stop Button

{
  "manifest_version": 2,
  "name": "Big Stop Button",
  "version": "1.0",
  "author": "Matthew Scheifer",
  "description": "Shows a centered stop button when navigating to new pages",
  "permissions": [
    "webNavigation"
  ],
  "background": {
    "scripts": [
      "constants.js",
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "constants.js",
        "content.js"
      ],
      "css": [
        "content.css"
      ],
      "run_at": "document_end"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "@big-stop-button.mscheifer",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}