Examine source code of cretix_colorify

{
  "manifest_version": 2,
  "name": "Colorify",
  "version": "2.5",
  "description": "Changes background to an image on webpages",
  "icons": {
    "48": "icons/border-48.png"
  },
  "applications": {
    "gecko": {
      "id": "Colorify@cretiX",
      "strict_min_version": "60.0"
    }
  },
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "icons/evelynn-32.png",
    "default_title": "Colorify",
    "default_popup": "popup/choose_background.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "default.js"
      ]
    }
  ]
}