Examine source code of Tab Colors

{
  "description": "Selects a random color for each tab",
  "manifest_version": 2,
  "name": "Tab Colors",
  "version": "2.6",
  "icons": {
    "48": "icons/color.png"
  },
  "permissions": [
    "theme",
    "tabs",
    "storage",
    "downloads"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  }
}