Examine source code of Foxy Calculator

{
  "name": "Foxy Calculator",
  "version": "1.2.0",
  "description": "A Firefox port of the popular Cloudy Calculator",
  "manifest_version": 2,
  "icons": {
    "16": "icons/16.png",
    "48": "icons/48.png",
    "128": "icons/128.png"
  },
  "browser_action": {
    "default_icon": "icons/19.png",
    "default_title": "Foxy Calculator",
    "default_popup": "popup.html"
  },
  "permissions": [
    "http://*.google.com/",
    "https://*.google.com/"
  ],
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Ctrl+Y"
      }
    }
  },
  "background": {
    "page": "background.html"
  }
}