Examine source code of Toggle Image Dimension

{
  "manifest_version": 2,
  "name": "Toggle Image Dimension",
  "version": "9.3.1",
  "description": "Hover over any image to see its natural and displayed dimensions, format, and file size. Toggle on/off via the toolbar button.",
  "browser_specific_settings": {
    "gecko": {
      "strict_min_version": "66.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      },
      "id": "{654fe38f-5219-4081-9b5a-87dbac13da88}"
    },
    "gecko_android": {
      "strict_min_version": "113.0"
    }
  },
  "permissions": [
    "activeTab"
  ],
  "icons": {
    "48": "resources/icon.svg",
    "96": "resources/icon.svg"
  },
  "browser_action": {
    "default_icon": "resources/icon.svg",
    "default_title": "Toggle Image Dimensions"
  },
  "background": {
    "scripts": [
      "src/background.js"
    ]
  }
}