Examine source code of the background

{
  "manifest_version": 2,
  "name": "Change Background Color",
  "version": "1.0",
  "description": "A simple extension to change the background color of a webpage",
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "browser_action": {
    "default_popup": "popup/popup.html",
    "default_icon": {
      "16": "icon.png"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{07318067-9326-41e0-b3b7-7bd83663fc62}"
    }
  }
}