Examine source code of Safe Select

{
  "manifest_version": 2,
  "name": "Safe Select",
  "version": "1.0.0",
  "description": "Temporarily disables navigation on the current tab so you can safely select and copy text. Resets automatically on refresh or navigation.",
  "icons": {
    "16": "icons/icon16.png",
    "32": "icons/icon32.png",
    "48": "icons/icon48.png",
    "96": "icons/icon96.png",
    "128": "icons/icon128.png"
  },
  "browser_action": {
    "default_icon": {
      "16": "icons/icon16.png",
      "32": "icons/icon32.png",
      "48": "icons/icon48.png",
      "96": "icons/icon96.png",
      "128": "icons/icon128.png"
    },
    "default_title": "Safe Select",
    "default_area": "navbar"
  },
  "permissions": [
    "activeTab"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "safe-select@local",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}