Examine source code of Major mnemonics

{
  "name": "Major",
  "version": "1.1",
  "description": "Displays mnemonic phrases for numbers",
  "manifest_version": 2,
  "icons": {
    "16": "16x16.png",
    "48": "48x48.png",
    "128": "128x128.png"
  },
  "background": {
    "scripts": [
      "major.js"
    ]
  },
  "permissions": [
    "notifications",
    "contextMenus"
  ],
  "browser_action": {
    "default_icon": "16x16.png",
    "default_popup": "major_popup.html"
  }
}