Examine source code of X-men icon

{
  "manifest_version": 2,
  "name": "X-men icon",
  "version": "1.0",
  "description": "The X-Men (a superhero group in the Marvel universe) logo is highly recognizable and iconic.",
  "icons": {
    "48": "icon.png"
  },
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html",
    "default_title": "Click me!"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{76d33095-9fc8-49af-97f7-5898fe1c0f77}"
    }
  }
}