Examine source code of Humidity meter icon

{
  "manifest_version": 2,
  "name": "Humidity meter icon",
  "version": "1.0",
  "description": "Humidity meter symbols often use sensors or data from devices to determine the humidity level of air or object.",
  "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": "{4f6b264f-6d08-41d8-bda1-f229db536c64}"
    }
  }
}