Examine source code of Hanzi Substitution

{
  "manifest_version": 2,
  "name": "Hanzi Substitution",
  "description": "Replaces words with hanzi.",
  "version": "0.2.2",
  "icons": {
    "16": "icons/icon16.png",
    "32": "icons/icon32.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "./substitute.js"
      ]
    }
  ],
  "permissions": [
    "storage"
  ],
  "browser_action": {
    "default_popup": "options.html"
  }
}