Examine source code of set page colors

{
  "name": "set page color",
  "description": "A browser action with a popup that changes the page color",
  "version": "1.0",
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_title": "Set this page's color.",
    "default_icon": "icon.png",
    "default_popup": "popup.html"
  },
  "manifest_version": 2,
  "browser_specific_settings": {
    "gecko": {
      "id": "{d60d9601-0759-4053-95de-26bd42a601f2}"
    }
  }
}