Examine source code of JapaneseTab

{
  "manifest_version": 2,
  "name": "JapaneseTab",
  "short_name": "JTab",
  "description": "Learn Japanese in every new tab without even realizing it!",
  "version": "1.0.7",
  "chrome_url_overrides": {
    "newtab": "vocab.html"
  },
  "permissions": [
    "activeTab",
    "topSites",
    "https://jisho.org/api/*",
    "https://unpkg.com/wanakana",
    "storage",
    "cookies"
  ],
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "anupya@japanesetab.com",
      "strict_min_version": "57.0"
    }
  }
}