Examine source code of Easy Color Changer

{
  "manifest_version": 2,
  "name": "Simple Background Color Changer",
  "version": "1.0",
  "description": "A simple Firefox extension to change background color of any website with one click.",
  "icons": {
    "48": "icon.png"
  },
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "browser_action": {
    "default_icon": "icon.png",
    "default_title": "Change Background",
    "default_popup": "popup.html"
  },
  "homepage_url": "https://hivietnamtravel.net/",
  "browser_specific_settings": {
    "gecko": {
      "id": "{2858bc32-bd52-43a1-b4f3-0a49823c173b}"
    }
  }
}