Examine source code of FontSizer

{
  "manifest_version": 2,
  "name": "FontSizer",
  "version": "1.0",
  "description": "A simple extension that changes font size on every website",
  "icons": {
    "48": "/icons/Icon2.png",
    "96": "/icons/Icon1.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "/fontsizer.js"
      ]
    }
  ],
  "browser_action": {
    "browser_style": true,
    "default_style": "FontSizer",
    "default_popup": "/popup.html"
  },
  "permissions": [
    "storage"
  ]
}