Examine source code of Custom Background Color

{
  "manifest_version": 2,
  "name": "Custom Background Color",
  "version": "1.2",
  "description": "Change the background color of web pages",
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html"
  },
  "icons": {
    "48": "icon.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{4cbf0722-fed5-4dab-954d-77a979dd2636}"
    }
  }
}