Examine source code of Coolor Palette Extractor

{
  "manifest_version": 2,
  "name": "Color Palette Display",
  "version": "1.0",
  "description": "A color palette generator and manager",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "permissions": [
    "storage",
    "activeTab"
  ],
  "browser_action": {
    "default_popup": "popup/index.html",
    "default_icon": {
      "48": "icons/icon-48.png",
      "96": "icons/icon-96.png"
    },
    "default_title": "Color Palette Display"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "color-palette-display@yourdomain.com"
    }
  }
}