Examine source code of newtab for poweruser

{
  "manifest_version": 2,
  "name": "addon_newtab_poweruser",
  "version": "1.2.1",
  "description": "the new tab for powerusers.",
  "homepage_url": "https://github.com/aloisleclet/addon_newtab_poweruser",
  "icons": {
    "48": "./icons/icon48.png",
    "96": "./icons/icon96.png",
    "128": "./icons/icon128.png",
    "256": "./icons/icon256.png",
    "500": "./icons/icon500.png"
  },
  "browser_action": {
    "default_icon": "./icons/icon96.png",
    "default_title": "newtab poweruser"
  },
  "chrome_url_overrides": {
    "newtab": "./newtab/newtab.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "webNavigation",
    "browserSettings",
    "storage",
    "tabs",
    "*://*/*"
  ]
}