Examine source code of Color Picker Pro1

{
  "manifest_version": 2,
  "name": "Color Picker Pro",
  "version": "1.0",
  "description": "Pick any color from the screen using EyeDropper API. Copy HEX/RGB and keep history.",
  "permissions": [
    "storage",
    "clipboardWrite"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "128": "icon128.png"
    }
  },
  "icons": {
    "128": "icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{625abdb8-038f-46f0-b34c-388c0a3e3629}"
    }
  }
}