Examine source code of Font Sizer

{
  "manifest_version": 2,
  "name": "Font Sizer",
  "version": "2.0",
  "description": "Easily change the font size of paragraphs.",
  "icons": {
    "48": "icons/FontSizer-Icon.png"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "icons/FontSizer-Icon.png",
    "default_title": "Font Sizer",
    "default_popup": "popup/popup.html"
  },
  "background": {
    "scripts": [
      "background_scripts/background.js"
    ]
  }
}