Examine source code of Duo Passcode Generator

{
  "name": "Duo Passcode Generator",
  "description": "Generates HOTP Passcodes for Duo Security Multi-Factor Authentication",
  "version": "2.0.1",
  "manifest_version": 2,
  "background": {
    "page": "background.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.duosecurity.com/*"
      ],
      "js": [
        "content.js"
      ],
      "all_frames": true
    }
  ],
  "permissions": [
    "storage",
    "*://*.duosecurity.com/*"
  ],
  "browser_action": {
    "default_popup": "./popup.html"
  },
  "icons": {
    "16": "./assets/icons/icon16.png",
    "48": "./assets/icons/icon48.png",
    "128": "./assets/icons/icon128.png"
  },
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Alt+Shift+D"
      }
    }
  },
  "applications": {
    "gecko": {
      "id": "duo@extension"
    }
  }
}