Examine source code of Flash Cardon

{
  "manifest_version": 2,
  "name": "Flash Cardon",
  "description": "Language learning aid",
  "version": "1.0.2",
  "icons": {
    "16": "icon_16.png",
    "19": "icon_19.png",
    "48": "icon_48.png",
    "128": "icon_128.png"
  },
  "browser_action": {
    "default_icon": "icon_19.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "permissions": [
    "activeTab",
    "storage",
    "contextMenus",
    "unlimitedStorage"
  ]
}