Examine source code of Photo icon

{
  "manifest_version": 2,
  "name": "Photo icon",
  "version": "1.0",
  "description": "An icon is an image used in an application, software, or operating system to represent an image.",
  "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": "{030e5dc0-b705-488e-85c2-31a8aa755dfa}"
    }
  }
}